SECTION
The freezing point of water
3
PRACTICAL
You are going to investigate the effect of dissolving different amounts of sodium chloride,
common salt, on the freezing point of water.
Safety
Apparatus (per group)
•
250 cm3 beaker
•
25 cm3 measuring cylinder
•
spatula
•
stirring rod
•
thermometer
•
test tube
•
crushed ice
•
salt
•
water
•
access to an electronic balance
Avoid getting salt into your
eyes.
Method
1
Use the measuring cylinder to add 25 cm3 of water to the beaker.
2
Add enough crushed ice so that the beaker is about half full. Stir the ice and water
with the stirring rod (do not use the thermometer to do this).
3
Measure and record the temperature of the ice/water mixture.
4
Add 2 g of salt to the mixture and stir with the stirring rod.
5
Measure and record the temperature of the mixture.
6
Repeat steps 4 and 5 until you have added a total of 10 g of salt.
7
Put approximately 2 cm3 of water in a test tube. Put the test tube into the mixture in
the beaker. Observe and record what happens to water in the test tube.
Recording your results
1
Make a suitable table to record all your results. The independent variable should be
recorded in the first column and the dependent variable in the second column.
Remember to include appropriate units in the column headings.
2
Plot a graph of temperature (°C) against mass of salt added (g). Draw a line of best fit.
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The freezing point of water
3
Considering your results/conclusion
3 Describe any pattern shown by your results. Does the temperature of the mixture in
the beaker change as the mass of salt added increases? If so, in what way?
4 Use your graph to predict the temperature you would have obtained if you had
added 5 g and 7 g of salt in your experiment. What temperature might you have
obtained if you had added 20 g of salt?
5 The accepted value for the freezing point of water is 0 °C. What temperature did you
record in step 3 in the method (before you added any salt)? How close to the accepted
value for the freezing point of water is this?
6 Explain what happened to the water in the test tube at the end of the investigation.
Include ideas from the particle theory in your explanation.
7 Ice cream can be made from a mixture of milk, cream and sugar using a cooling bath
containing ice, water and salt. Suggest why this works.
Evaluation
8 Identify any anomalous results in your investigation, and whether they appeared to be
too low or too high.
9 Suggest a reason for anomalous results in this investigation (even if you did not have
any).
10 Compare your results with the results obtained from other groups. How reliable were
your results? Suggest reasons for any differences between the sets of results.
11 All groups should have obtained the same temperature for the ice/water mixture at the
start of the investigation (0 °C if pure ice and water was used). Suggest a reason for
any differences observed.
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SECTION
3
Treating water
PRACTICAL
You are going to make a simple filtration unit to remove insoluble contaminants from water.
Safety
Apparatus (per group)
•
plastic drinks bottle, top half
•
sand
•
cotton wool
•
small stones or gravel
•
stand, boss and clamp
•
2 × 100 cm3 beakers
•
evaporating basin
•
muddy water
Do not drink the water from the
filter.
Method
1
Clamp the drinks bottle upside down by its neck.
stones
sand
cotton wool
2
Gently pack the neck with cotton wool. Make a filter bed by adding some sand
followed by a layer of small stones. Measure and record the depth of the sand layer.
3
Put a beaker under the neck of the drinks bottle, and add clean tap water to the top of
the filter bed. Repeat until the filtrate runs clear, then pour it away.
4
Put the evaporating basin under the neck of the drinks bottle. Mix some soil and water
together, and then pour it into the filter bed.
5
Collect the filtrate in the evaporating basin. Observe and record its appearance.
6
Leave the evaporating basin aside for several days to allow the water to evaporate.
Observe and record the appearance of any residue left behind in the basin.
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Treating water
3
Recording your results
1
Make a suitable table to record all your results. You will be recording the depth of the
sand layer, and the appearance of the filtrate before and after evaporating the water.
Considering your results/conclusion
2 Consider the appearance of the filtrate from the muddy water. Was it clear and
colourless?
3 Why might the filtrate be cloudy?
4 Why might the filtrate be coloured?
5 Consider the appearance of the residue after the water was evaporated from the
filtrate. Could you see any individual pieces of material? Was the residue coloured or
colourless?
6 Why might the residue contain individual pieces of material?
7 Why might the residue be coloured?
8 To what extent was your filter bed successful at treating the muddy water?
Evaluation
9 What was the purpose of the cotton wool?
10 Why did you run tap water through the filter bed first?
11 Compare your results with the results obtained from other groups. Did the depth of the
sand bed make any difference to success of the filter bed? Suggest reasons for any
differences in the success of the filter beds.
12 Why would the filtered water still not be safe to drink?
13 Describe how water at a water treatment works would be made safe to drink after
filtering it.
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SECTION
3
pH testing – part one
PRACTICAL
In the first part of the experiment you are going to make an indicator solution from red
cabbage. In part two, you will test various substances with your indicator (and also with
litmus and universal indicator).
Safety
Apparatus (per group)
•
chopping board and knife
Wear eye protection.
•
pestle and mortar
•
filter funnel
Take care when cutting up the
red cabbage.
•
filter paper
•
conical flask
•
red cabbage
•
sand
•
hot water
Take care when handling hot
water.
Method
1
Carefully cut some red cabbage leaves into small pieces.
2
Transfer the pieces of red cabbage to the mortar. Add a little sand and hot water.
3
Use the pestle to grind the pieces of red cabbage so you get as much colour out of
the leaves as you can.
4
Set up a conical flask, filter paper and funnel.
5
Filter the mixture, collecting the filtrate in the conical flask. This is your red cabbage
indicator.
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SECTION
3
pH testing – part two
PRACTICAL
You are going to test various substances with different indicators.
Safety
Apparatus (per group)
•
spotting tile
Wear eye protection.
•
glass rod
•
dropping pipette
•
universal indicator paper
•
universal indicator pH colour chart
Do not taste any of the test
substances. If you spill any of
them on your clothing or skin,
remove the contaminated
clothing and wash the skin with
plenty of water.
•
red litmus paper and blue litmus paper
•
red cabbage indicator (prepared in part one)
•
substances to test
Method
You may wish to carry out these tests, using water as the first test substance.
6
Add a few drops of cabbage indicator to a well in the spotting tile. Add a few drops of
the test substance and record the colour obtained. Wash out the dropping pipette.
7
Onto a clean part of the spotting tile, put a piece of universal indicator paper, a piece
of red litmus paper, and a piece of blue litmus paper.
8
Rinse the glass rod with water and then dip it into one of the test substances.
9
Touch the glass rod against each of the three indicator papers in turn so that a small
spot of liquid is transferred to each one. Try to avoid adding so much liquid that the
colour runs out of the paper.
10 After about 30 seconds, record the colour of the spots on each indicator paper.
Match the colour of the universal indicator paper spot to a colour on the colour chart,
and record the corresponding pH value.
11 Repeat steps 6 to 10 with the remaining test substances. If you are unsure about any
of the observations, repeat the test again for that substance.
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pH testing
3
Recording your results
1
Make a suitable table to record all your results. The table below shows some
suggested headings.
Substance
Colour
with red
cabbage
Colour with
red litmus
Colour with
blue litmus
Colour with
universal
indicator
pH
Considering your results/conclusion
2 List the different test substances in pH order, from the lowest pH to the highest pH.
3 Identify any neutral substances from your results. What colour does each of the four
indicators have when neutral substances are added to them?
4 Identify the most acidic substance from your results. What colour does each of the
indicators have when strongly acidic substances are added to them?
5 Identify the most alkaline substance from your results. What colour does each of the
indicators have when strongly alkaline substances are added to them?
6 Copy and complete this table to summarise the colours seen with litmus paper:
Type of
substance
Colour with
red litmus
Colour with
blue litmus
acidic
neutral
alkaline
Evaluation
7 Describe any difficulties you might have experienced carrying out this experiment.
8 Did you have to repeat any of the tests? If so, explain why you did this.
9 Compare your results with those obtained by other groups. How reliable were your
results? Suggest reasons for any differences between the sets of results.
10 Blue litmus paper stays blue with a certain substance. Explain why you cannot be sure
that the substance is alkaline, and how you could confirm whether or not it is alkaline
using litmus paper.
11 Compare universal indicator paper with red and blue litmus papers and red cabbage
indicator. Discuss the advantages and disadvantages of using each type of indicator
paper.
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SECTION
3
Testing vinegar
PRACTICAL
You are going to use titration to find out which sample of vinegar contains the most acid.
Apparatus (per group)
Safety
•
burette and stand
Wear eye protection.
•
white tile
•
25 cm3 measuring cylinder
Vinegar forms an irritating
vapour with a sharp smell.
•
250 cm3 conical flask
•
2 × 100 cm3 beakers
•
dropping pipette
•
filter funnel
•
vinegar samples A and B
•
sodium hydroxide solution
•
phenolphthalein indicator
Dilute sodium hydroxide is an
irritant.
Avoid getting phenolphthalein
on your skin.
The burette is a long piece of
apparatus. Do not over-reach
to fill it – put the burette and its
stand on a flat lab stool or on
the floor to fill it if you cannot
reach the top easily.
Method – part one
1
Clamp the burette firmly. Make sure the burette is vertical with
the tap at the bottom. Turn the tap so that it is off (turn to the
horizontal position).
2
Put the white tile on the base of the burette stand – then put a
beaker on the white tile.
3
Half-fill another beaker with water and pour this into the burette.
Open the tap (turn it to the vertical position) and let the water run
out. This cleans the burette.
4
Close the tap. Add some of one of the vinegar samples to the
burette using the funnel, and then open the tap to run this waste
into the beaker. Close the tap and then top up with vinegar to
just below the 0.0 cm3 mark.
5
Measure 25 cm3 of the sodium hydroxide solution and pour this
into the conical flask. Add a few drops of phenolphthalein
indicator.
6
Put the conical flask under the burette, adjusting the height of the
burette if needed.
7
Record the start burette reading. Open the tap a little. As the
vinegar runs into the conical flask, gently swirl the flask to keep
the liquids mixed. As soon as a permanent purple tinge appears,
close the tap again. Record the end burette reading.
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Testing vinegar
3
Method – part two
8
Empty the flask and wash it out. Repeat steps 5 to 7.
9
Open the tap to run the remaining vinegar into the flask. Empty the flask and wash it.
10 Repeat steps 3 to 8 with the other vinegar sample.
Recording your results
1
Make a suitable table to record all your results. The table below shows some
suggested headings.
Vinegar A
(run 1)
Vinegar A
(run 2)
Vinegar B
(run 1)
Vinegar B
(run 2)
End burette reading (cm3)
Start burette reading (cm3)
The ‘titre’ – end reading
minus start reading (cm3)
Considering your results/conclusion
2
The ‘titre’ is the volume of acid needed to neutralise the alkali – it is the difference
in cm3 between the burette reading at the end and the burette reading at the start.
Calculate the mean titre for each vinegar sample.
3
The weaker the vinegar, the greater the volume needed to neutralise the sodium
hydroxide solution. Which sample of vinegar, A or B, is the weakest? How do you
know?
Evaluation
4
Describe any difficulties you experienced carrying out this experiment.
5
How close to each other are the titres from run 1 and run 2 for each vinegar sample?
Suggest why the two titres might be different from each other, when they ought to be
the same.
6
How confident are you that you have identified the weaker vinegar sample? Give
reasons for your answer.
7
Compare your results with the results obtained by other groups. How reliable were
your results? Suggest reasons for any differences between the sets of results.
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SECTION
Making copper sulphate
3
PRACTICAL
You are going to make dry copper sulphate crystals from copper oxide and sulphuric acid.
Apparatus (per group)
Safety
•
2 × 250 cm3 beakers
•
boiling tube
Wear eye protection.
•
test tube rack
•
test tube holder
Take care when handling hot water and hot
sulphuric acid.
•
spatula
•
filter paper
•
filter funnel
•
stand, boss and clamp
•
evaporating basin
•
dilute sulphuric acid
•
copper oxide powder
•
access to a kettle
•
access to an electronic balance
Dilute sulphuric acid is an irritant. If you spill
any on your clothing or skin, remove the
contaminated clothing and wash the skin with
plenty of water.
Copper oxide is harmful. Avoid contact with
your skin.
Copper sulphate is harmful if swallowed. It is
an irritant if it gets into your eyes.
Method – part one
1
Add 15 cm3 of sulphuric acid to a boiling tube supported in a test tube rack.
2
Half-fill a 250 cm3 beaker with near boiling water from a kettle. Put the boiling tube
from step 1 into the beaker of hot water.
3
Weigh out approximately 2 g of copper oxide powder onto a small piece of paper. Use
the spatula to divide the powder into four quarters on the paper.
4
Carefully add one quarter of the copper oxide powder to the boiling tube of sulphuric
acid. Lift the boiling tube from the water and gently shake it from side to side.
5
Allow time for the mixture to turn clear rather than cloudy – then repeat step 4.
6
Prepare another beaker half-filled with near boiling water from the kettle. Transfer the
boiling tube to this beaker of hot water and repeat step 4.
7
Add the last quarter of copper oxide powder to the boiling tube. Lift the boiling tube
from the water and gently shake it from side to side. Repeat the shaking from time to
time over the next five minutes. The mixture will not go clear this time.
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Making copper sulphate
3
Method – part two
8
Fold a piece of filter paper and put it into a filter funnel. Clamp the filter funnel over the
evaporating basin.
9
Use a test tube holder to hold the boiling tube by its neck, and pour the contents into
the filter funnel.
10 Collect the filtrate in the evaporating basin. Record the appearance of the residue in
the filter paper and of the filtrate.
11 Put the evaporating basin aside for a few days to allow the water to evaporate.
Inspect the crystals of copper sulphate formed and record your observations.
Recording your results
1
Make a suitable table to record your observations during the investigation, such as:
• what happens when the copper oxide powder is added to hot sulphuric acid
• the appearance of the residue in the filter paper
• the appearance of the filtrate in the evaporating basin
• the appearance of the copper sulphate crystals.
Considering your results/conclusion
2 Write a word equation for the reaction between sulphuric acid and copper oxide.
3 Why did you need to heat the sulphuric acid?
4 Why did you use a hot water bath, rather than heating the acid with a Bunsen flame?
5 Copper oxide is insoluble in water. Suggest why the copper oxide powder disappeared
at first when added to the sulphuric acid, but later some of it remained undissolved.
Why was it important to make sure that extra (excess) copper oxide was added to the
acid?
6 Why was the reaction mixture filtered?
7 Identify the residue in the filter paper and the filtrate in the evaporating basin.
Evaluation
8 Describe any difficulties you experienced carrying out this experiment.
9 Compare the quality and appearance of your crystals with those obtained by other
groups. Suggest reasons for any differences observed.
10 Your teacher said that you should have made just over 7.0 g of copper sulphate
crystals. Suggest why you have made less than 7.0 g of crystals.
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SECTION
3
Acid rain
PRACTICAL
Sulphur dioxide is one of the gases that causes acid rain. You are going to investigate its
effects on seeds and building materials.
Apparatus (per group)
Safety
•
2 plastic containers with close-fitting lids
Wear eye protection.
•
2 dropper pipettes
•
2 Petri dishes with lids
•
cotton wool
•
cress seeds
•
various substances to test
•
sodium metabisulphite solution
•
magnifying glass
Sodium metabisulphite solution
smells because it releases
small amounts of sulphur
dioxide. This is a toxic gas with
a choking sharp smell. It might
cause an asthma attack if you
suffer from asthma. Only use
what you need, work with
plenty of ventilation and do not
breathe in over the solution.
Method – part one
1
Line two Petri dish lids with a shallow layer of cotton wool. Add some tap water to
dampen the cotton wool. Sprinkle an equal number of cress seeds over each layer of
damp cotton wool. Put the completed Petri dish lids into the bottom of the plastic
containers, one lid per container.
2
Collect two samples of each test substance as provided by your teacher. These will
include small pieces of different metals, building materials and rocks. Aim to choose
similar pieces of each test substance.
3
Use the magnifying glass to examine each test substance and a cress seed. Record
your observations.
4
Arrange the test substances next to the Petri dish of cress seeds in the bottom of
each plastic container. Leave space in each plastic container for a Petri dish bottom.
5
Line two Petri dish bottoms with a shallow layer of cotton wool.
6
Use a dropper pipette to add some water to one of the Petri dish bottoms. Put the
Petri dish bottom in the bottom of one of the plastic containers. Carefully fit the lid to
the plastic container and label it with your names and the date, and ‘no SO2’.
7
Repeat step 6 with the other Petri dish bottom and plastic container, but this time use
the other dropper pipette to add the same volume of sodium metabisulphite solution.
Label this plastic container with your names and the date, and ‘with SO2’.
8
Leave both plastic containers aside for a few days.
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Acid rain
3
Method – part two
9
After a few days, open each plastic container to examine its contents. Open the
‘with SO2’ plastic container in the fume cupboard and leave its Petri dish of
sodium metabisulphite solution in there. Use the magnifying glass to examine
each test substance and the cress. Record your observations.
Recording your results
1
Make a suitable table to record your observations during the investigation. You will
need space to record the appearance of the test substances and cress:
•
before adding them to the containers
•
after leaving one of each in the container without sulphur dioxide
•
after leaving one of each in the container with sulphur dioxide.
Considering your results/conclusion
2
What was the purpose of the sodium metabisulphite solution?
3
Why did you use one container with sodium metabisulphite and one with water?
4
Describe the differences observed in the development of the cress in the two
environments. What effect does the presence of sulphur dioxide have on the cress?
5
Describe the differences observed in the appearance of the metals in the two
environments. Were any of the metals damaged by the presence of sulphur dioxide?
Did any of them appear to be not damaged by the presence of sulphur dioxide?
Suggest a reason why this might be.
6
Describe the differences observed in the appearance of the plastic, rocks and building
materials in the two environments. Were any of them damaged by the presence of
sulphur dioxide? Did any of them not appear to be damaged by its presence?
7
Suggest which materials would be best suited to constructing buildings in heavily
polluted environments. Explain your answer and outline any problems to builders that
such a choice of materials might cause.
Evaluation
8
How reliable are your results? Compare your results with those obtained by other
groups, and suggest reasons for any differences observed.
9
How confident are you that you can draw firm conclusions from your experiment?
10 How would you improve the experiment, if you had to do it again?
11 Describe how you might extend the experiment.
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SECTION
The freezing point of water
3
PRACTICAL
Teacher and Technician sheet
Safety
Sodium chloride presents a low hazard.
Wear eye protection.
Resources (per group of pupils)
Notes
250 cm3 beaker
This can be glass or plastic.
25 cm3 measuring cylinder
Pupils will be measuring out 25 cm3 of
water.
spatula
This is so that pupils can weigh out
sodium chloride – it could be provided
next to the balance rather than per
group.
stirring rod
thermometer
Provide alcohol thermometers rather
than mercury thermometers. The
minimum temperature reading should be
−10 °C or lower.
test tube
crushed ice
Each group needs about 100 cm3 of
crushed ice.
sodium chloride
Table salt can be used instead.
electronic balance
The balance should read to a minimum
precision of ±0.1 g. Two or more groups
could share a balance.
de-ionised water
Tap water would do instead.
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SECTION
3
Treating water
PRACTICAL
Teacher and Technician sheet
Safety
Take care to avoid sharp edges when cutting the plastic drinks bottles in half.
Resources (per group of pupils)
Notes
plastic drinks bottle
Use empty 2 litre plastic drinks bottles.
Cut each bottle in half around the middle.
The pupils need the top half with the
neck.
sand
Use children’s play sand rather than
builders’ sand.
cotton wool
small stones or gravel
If possible, wash the gravel beforehand
in a bucket of water.
stand, boss and clamp
2 × 100 cm3 beakers
These may be glass or plastic.
evaporating basin
soil
You may wish to put out old spoons with
the soil so that the pupils can mix it with
water.
Resources (per class)
Notes
Waste bin lined with a plastic bin sack
The pupils will need to dispose of the
excess soil and their filter bed when
finished. You may wish to return the
muddy water to the ground outside, and
to recycle the sand and gravel by
washing it in buckets of water.
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SECTION
pH testing – part one
3
PRACTICAL
Teacher and Technician sheet
Safety
Low hazard presented.
Resources (per group of pupils)
Notes
chopping board and knife
Consider chopping the red cabbage
leaves before supplying them to the
pupils to avoid using knives.
pestle and mortar
filter funnel
filter paper
conical flask
100 cm3 capacity would be suitable – or
supply a boiling tube and test tube rack
instead.
red cabbage
sand
Optional – to improve the grinding of the
red cabbage leaves.
kettle
Bunsen burner, tripod, gauze and beaker
can be provided instead.
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SECTION
pH testing – part two
3
PRACTICAL
Teacher and Technician sheet
Safety
Eye protection must be worn when preparing the test substances.
Dilute the household liquids as necessary to avoid exposing pupils to strongly acidic or
alkaline solutions. Do not exceed 0.1 M for the laboratory acids and alkalis.
Label each container so that pupils know the identities of the substances they are testing.
Include appropriate hazard symbols – e.g. irritant for alkalis.
Resources (per group of pupils)
Notes
spotting tile
A plain ceramic tile can be used instead.
glass rod
dropping pipette
universal indicator paper
universal indicator colour chart
red litmus paper
blue litmus paper
water, a range of household liquids, laboratory
acids and alkalis
Select the substances so that pupils are
able to record a range of pH values.
Household substances might include:
• bleach
• lemon juice
• oven cleaner
• liquid soap
• vinegar
• washing powder
• washing-up liquid
Laboratory substances might include:
• hydrochloric acid
• sulphuric acid
• ammonia solution
• limewater
• sodium hydroxide solution
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SECTION
Testing vinegar
3
PRACTICAL
Teacher and Technician sheet
Safety
Ethanoic acid is corrosive. Wear eye protection (a face shield is best) and gloves and
work with a fume cupboard when diluting concentrated ethanoic acid.
Sodium hydroxide is corrosive. Wear eye protection (a face shield is best) and gloves and
work with a fume cupboard when preparing aqueous sodium hydroxide.
Resources (per group of pupils)
Notes
burette and burette stand
A stand, clamp and boss can be used
instead of a burette stand.
white tile
25 cm3 measuring cylinder
250 cm3 conical flask
2 × 100 cm3 beakers
dropping pipette
filter funnel
phenolphthalein indicator
This is best supplied in a labelled
dropping bottle.
vinegar sample A
Prepare a 0.10 M solution of ethanoic
acid (5.2 cm3 per dm3), or diluted white
distilled vinegar (1 part vinegar to 9 parts
water). Label it ‘Vinegar A’. Allow 75 cm3
per group. See the safety notes above.
vinegar sample B
Prepare a 0.09 M solution of ethanoic
acid (4.7 cm3 per dm3), or diluted white
distilled vinegar (1 part vinegar to 10
parts water). Label it ‘Vinegar B’. Allow
75 cm3 per group. See the safety notes
above.
0.075 M sodium hydroxide solution
(3 g NaOH per dm3)
Label it as irritant. Allow 125 cm3 per
group. See the safety notes above.
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SECTION
Making copper sulphate
3
PRACTICAL
Teacher and Technician sheet
Safety
Eye protection must be worn when preparing the sulphuric acid.
The copper(II) sulphate crystals produced in the investigation are an irritant if they get into
the eyes. The crystals could be used to prepare copper(II) sulphate solutions for use in
other practicals.
Pupils must not be allowed to take the copper(II) sulphate crystals out of the lab.
Resources (per group of pupils)
Notes
2 × 250 cm3 beakers
boiling tube
test tube rack
test tube holder
spatula
filter paper
filter funnel
stand, boss and clamp
evaporating basin
1.2 M sulphuric acid
Label it as irritant. Allow 25 cm3 per
group.
copper(II) oxide powder
Label it as harmful. Allow 2.5 g per
group.
kettle
You may wish to provide one kettle
between two or more groups of students.
electronic balance
The balance should read to a minimum
precision of ±0.1 g. Two or more groups
could share a balance.
You may wish to pre-weigh a 2 g portion
of copper(II) oxide powder onto pieces of
paper, or into small test tubes, for each
group instead of giving pupils access to
balances.
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SECTION
3
Acid rain
PRACTICAL
Teacher and Technician sheet
Safety
Eye protection must be worn when preparing the aqueous sodium metabisulphite
solution.
0.1 M sodium metabisulphite presents a low hazard, but inhalation of sulphur dioxide may
exacerbate pre-existing breathing conditions such as asthma. Teachers should be aware
of pupils who suffer from breathing problems because the smell of sulphur dioxide can be
detected from the solution.
The experiment takes two lessons. It would be advisable to have access to a fume
cupboard.
Resources (per group of pupils)
Notes
2 large plastic containers with airtight lids
Tupperware® or similar.
2 dropping pipettes
2 Petri dishes with lids
Each group needs four shallow dishes.
cotton wool
cress seeds
magnifying glass
If you have sufficient numbers, allow one
per pupil.
0.1 mol dm−3 sodium metabisulphite
19 g dm–3 sodium metabisulphite
Na2S2O5. Allow 15 cm3 per group.
various substances to test
The pupils are examining the effect of
‘acid rain’ on the cress seeds and various
materials. These materials could include
small pieces of:
• metals (e.g. iron, steel, copper, zinc,
aluminium, magnesium)
• plastic (e.g. PVC, polythene,
polystyrene)
• rock (e.g. chalk, limestone, granite)
• brick
• concrete.
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SECTION
3.1 Our water supply
3
Questions
1
River water must be treated to make it ‘potable’, or safe to drink. Make a flow chart to
show how river water is treated after collecting it in a reservoir. There is no need to
draw diagrams and you should use your own words. Start your flow chart like this:
[Total 6]
2
The table shows the different uses of potable water by people in the UK.
Use
Bath and shower
Dishwasher
Flushing toilet
Food preparation and drinking
Litres per person per day
46
8
36
5
Laundry
16
Other uses (garden, washing car etc.)
19
a) Draw an appropriate chart or graph to display the data in the table.
[4]
b) i)
[2]
List any uses that definitely need potable water. Explain your answer.
ii) List any uses that do not necessarily need potable water. Explain your
answer.
[2]
iii) Are there any uses that could be met by untreated water but are actually
best met by potable water? Explain your answer.
[2]
c) Consider the stages involved in treating river water to make it potable.
i)
Suggest which stage is likely to be the most costly and give your reasons.
[2]
ii) Apart from saving money, why might the government and water
companies want the public to reduce their consumption of water at home?
[2]
[Total 14]
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SECTION
3.2 Answers – not questions
Name
Date
3
Class
Acids, alkalis and neutralisation
There are fifteen answers in the table below. Decide on suitable questions for each answer
and write them in the table. Try your questions on a partner. Do they get the same answer as
you started with? Discuss any similarities and differences with your partner.
Answers without questions
Answer
1
A neutralisation reaction
2
Changes colour in acids
3
Alkaline
4
Ammonia
5
Corrosive
6
H2SO4
7
Hydrochloric acid
8
Less than pH 7
9
Magnesium hydroxide
10
pH 7
11
Red litmus paper
12
The pH scale
13
Titration
14
Universal indicator
15
Use baking soda
Question
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SECTION
3.3 Making salts
3
Cut out the jigsaw pieces and then use them to answer the questions below.
You will need to use some pieces more than once. Some compounds need three pieces
rather than just two.
Questions
1
a) Make these acids – hydrochloric acid (hydrogen chloride), nitric acid
(hydrogen nitrate), sulphuric acid (hydrogen sulphate).
b) Make these alkalis – sodium hydroxide, potassium hydroxide, magnesium
hydroxide, calcium hydroxide.
c) Make water (hydrogen hydroxide).
2
[Total 8]
Choose one acid and one alkali. Write down their names, and then rearrange the
pieces to form the salt and water. Write down the name of the salt, then the word
equation for the reaction. Repeat with the other acids and alkalis (there are 12
combinations).
[Total 12]
Do not print this sheet double-sided
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SECTION
Chlorination of drinking water
3
HSW
Killing harmful microorganisms
Chlorine gas has been used to disinfect drinking water in the UK for over 100 years. It reacts
with water at the water treatment works to produce a mixture of chloric acid and hydrochloric
acid. Harmful microorganisms are killed by chloric acid, but its concentration decreases as
the pH increases. For example, its concentration at pH 7.5 is about nine times lower than its
concentration at pH 6.5 (pure water is neutral at pH 7).
Most people can taste or smell chlorine in water when its concentration is as low as 5 mg per
litre. Some people can even detect it when its concentration is just 0.3 mg per litre.
Consumers complain when its concentration in drinking water rises above 0.6 mg per litre.
Chlorine reacts with compounds in water to form potentially hazardous substances, such as
trichloromethane. There is experimental evidence that this can cause cancer in laboratory
animals, but not enough evidence for it doing so in humans. Water companies take steps to
minimise the amounts of such compounds in water and levels are constantly monitored.
Scientists estimate that the risk of getting cancer from the by-products of chlorination is
between a 100 and 1000 times less than the risk of dying from swallowing harmful
microorganisms in untreated water.
Questions
1
a) Which acids are formed when chlorine dissolves in water?
[2]
b) Name the acid responsible for killing microorganisms in water.
[1]
c) Suggest why the World Health Organisation (WHO) recommends that the pH
of drinking water should be less than 8.
[1]
d) Swimming pool water is kept at around pH 7.3 by adding sodium carbonate.
Suggest why a lower pH is not chosen, even though this would be better for
killing harmful microorganisms.
[1]
[Total 5]
2
a) Suggest why WHO recommends a minimum of 5 mg chlorine per litre in
drinking water.
[1]
b) About 0.5 mg chlorine per litre is added to water at UK water treatment plants.
i)
Explain why this amount might have been chosen.
[1]
ii) Suggest why the actual concentration of chlorine in the water coming out
of our taps may be lower than 0.2 mg per litre.
c) Why is the concentration of chlorine in swimming pools around 3 mg per litre?
[2]
[2]
[Total 6]
3
Discuss the advantages and disadvantages of chlorinating drinking water. Why does it
continue to be done when harmful substances are known to form as a result?
[Total 4]
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SECTION
3
Joseph Black and chalk
HSW
In 1755, Joseph Black reported on his experiments with chalk, an almost pure form of
calcium carbonate. Read the information about his experiments and then answer the
questions.
Experiment 1
Black weighed a piece of chalk, He then added a weighed amount of hydrochloric acid to it.
He waited until the mixture stopped fizzing and weighed the mixture. He found that its mass
was less than it had been before the reaction.
Experiment 2
Black took a piece of chalk that weighed the same as the first one. He heated it strongly and
was left with a piece of white solid, called quicklime. He weighed the piece of quicklime. He
found that it weighed less than the chalk had done. The loss in mass was the same as the
loss in mass during Experiment 1.
Experiment 3
Black took the piece of quicklime from Experiment 2. He added to it the same weight of
hydrochloric acid as he had used in Experiment 1. There was no fizzing or loss of mass.
Experiment 4
Black dissolved quicklime in water to make limewater. He found that a dish of this went
cloudy during a church service attended by 1500 people, but not in the same empty church.
Questions
1
a) Copy and complete these word equations:
i)
calcium carbonate + hydrochloric acid → ______ + ______ + ______
[3]
ii) calcium carbonate → calcium oxide + ______________________
[1]
iii) calcium oxide + hydrochloric acid → _________ + _________
[2]
b) Explain why improvements in weighing technology were important to Black’s
experiments with chalk.
[1]
c) What are the chemical names for chalk and quicklime?
[2]
[Total 9]
2
a) Why did Black use identical masses of chalk in Experiments 1 and 2?
[1]
b) Suggest why Black concluded that the loss of mass in Experiments 1 and 2
was caused by the loss of a gas.
[2]
[Total 3]
3
a) Explain why the limewater went milky white during the church service.
[2]
b) Why did Black repeat Experiment 4 in the empty church?
[1]
[Total 3]
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SECTION
3
Sulphuric acid
HSW
Read this extract from a newspaper article about sulphuric acid and answer the questions.
Sulphuric acid prices go mad
Sulphuric acid prices have seen a huge increase
in recent months after several years of decline.
They have reached £200 per tonne six months
after a low of just £50 per tonne. Several
factors seem to be involved: the world price of
sulphur is rising; there is an increased demand
for sulphuric acid for fertiliser manufacture;
and sulphuric acid itself is in short supply.
The UK Government’s Renewable Transport
Fuel Obligation means that 5% of fuel must
come from renewable sources by 2010. An
increased demand for bioethanol to fuel cars
has added to the demand for sulphuric acid. A
typical bioethanol factory needs several
thousand tonnes of the acid each year.
Questions
1
a) By how much did the price of sulphuric acid increase in six months?
[1]
b) Give two uses of sulphuric acid mentioned in the article.
[2]
[Total 3]
2
a) Sulphuric acid is manufactured by the Contact Process. Copy and complete
this word equation for the first stage in this process:
sulphur + _____________ → sulphur dioxide
[1]
b) Explain why the cost of sulphur would affect the cost of sulphuric acid.
[1]
c) Suggest why the cost of sulphur might increase.
[2]
[Total 4]
3
In the UK, bioethanol is manufactured from sugar or wheat. Around 9 kg of sugar
beet must be grown for each litre of bioethanol produced.
a) Suggest why an increase in the demand for bioethanol might cause an
increase in the demand for fertilisers.
[1]
b) Explain how the demand for fertilisers affects the demand for sulphuric acid.
[2]
c) Some people see a rising demand for bioethanol as a ‘double whammy’ for
the demand for sulphuric acid. They mean that bioethanol demand involves
two factors that affect the demand for sulphuric acid. Identify these factors.
[2]
[Total 5]
4
Used sulphuric acid can be recycled, but this is costly. Explain why recycling sulphuric
acid is becoming more attractive. What are the advantages and disadvantages of
recycling sulphuric acid compared to manufacturing it from sulphur?
[Total 4]
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SECTION
3
Symbol equations
EXTENSION
You are going to write symbol equations for some neutralisation reactions.
Use the information below to help you to answer the questions.
Word equations
Here are the general word equations for neutralisation reactions involving bases:
•
acid + metal oxide → salt + water
•
acid + metal hydroxide → salt + water
•
acid + metal carbonate → salt + water + carbon dioxide
Symbol equations
A word equation shows the reactants and products in a chemical reaction, but it is not
quantitative. Word equations do not give information about the numbers of atoms and
molecules involved. So chemists usually use symbol equations instead.
In a symbol equation, there must be the same number of atoms of each element on both
sides of the equation. If the number of atoms of one or more elements is not the same, the
equation is not balanced.
For example, this equation is not balanced:
HCl + CuO → CuCl2 + H2O
The formulae are correct and cannot be changed, but there are two hydrogen atoms and two
chlorine atoms on the right, and only one of each on the left. A number ‘2’ is put in front of
the formula for HCl in the equation to balance it:
2HCl + CuO → CuCl2 + H2O
Chemical formulae
The chemical formula of a substance shows the number of atoms of each element it
contains. The table shows the formulae of some salts. The small numbers show how many
atoms, or groups of atoms, there are in the compound. For example:
•
in CuCl2 there is one copper atom and two chlorine atoms
•
in Cu3(PO4)2 there are three copper atoms and two phosphate groups (PO4)
Name of salt
Formula
Name of salt
Formula
copper chloride
CuCl2
magnesium phosphate
Mg3(PO4)2
copper nitrate
Cu(NO3)2
magnesium sulphate
MgSO4
copper phosphate
Cu3(PO4)2
sodium chloride
NaCl
copper sulphate
CuSO4
sodium nitrate
NaNO3
magnesium chloride
MgCl2
sodium phosphate
Na3PO4
magnesium nitrate
Mg(NO3)2
sodium sulphate
Na2SO4
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Symbols equations
3
Questions
1
Copy the table below. Leave plenty of space in the empty boxes for names and
formulae. Complete your table by writing in the name and formula of the salt formed
when each acid and base react with each other. One has been done for you.
Base
sodium
hydroxide
Acid
NaOH
copper
oxide
CuO
hydrochloric
HCl
acid
nitric acid
HNO3
sulphuric
acid
H2SO4
phosphoric
acid
H3PO4
magnesium
carbonate
MgCO3
magnesium
chloride
MgCl2
[Total 11]
2
a) Write the word equations for the reactions in question 1.
For example:
hydrochloric
magnesium
magnesium
carbon
+ carbonate →
+ water + dioxide
acid
chloride
[11]
b) Underneath each name in the word equations you have written in part a)
write the formulae of each compound. For example:
hydrochloric
magnesium
magnesium
carbon
+ carbonate →
+ water + dioxide
acid
chloride
HCl
MgCO3
MgCl2
H2O
CO2
[11]
c) Complete the balanced symbol equation for each reaction, adding numbers if
needed. For example:
hydrochloric
magnesium
magnesium
carbon
+
+
water
+
→
acid
carbonate
chloride
dioxide
2HCl
+
MgCO3
MgCl2
+ H2O +
CO2
→
[11]
[Total 33]
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SECTION
The nature of acids
3
EXTENSION
Ideas about acids have changed over time. The table below shows some of the scientists
who were involved and what they did. Use the information to help you answer the questions.
1
In 1766, Cavendish
was able to make
‘inflammable air’. This
gas produced dew on
the inside of its
container when it was
burned in air. He
concluded that
inflammable air
produces water when it
burns.
2
Henry Cavendish
Joseph Priestley
(1731–1810)
(1733–1804)
3
Carl Scheele
In 1774, Scheele
dissolved marine acid
air in water to make
‘muriatic acid’. He
added this acid to a
mineral containing
manganese dioxide.
The reaction made a
pale green-yellow gas
that was later called
‘oxy-muriatic acid’.
(1742–1786)
5
Humphry Davy
(1778–1829)
4
Antoine Lavoisier
(1743–1794)
In 1810, Davy showed
that oxy-muriatic acid
did not contain oxygen
and could not be
broken down. He
discovered that
muriatic acid contained
hydrogen and one
other element. He
called this chlorine,
from the Greek word
for pale green.
In 1772, Priestley
added concentrated
sulphuric acid to
sodium chloride. The
reaction made an
acidic gas that he
called ‘marine acid air’.
In 1774, he heated
mercury oxide. The
reaction made mercury
and a colourless gas
that he called
‘dephlogisticated air’.
Lavoisier carried out
lots of experiments,
particularly those
involving burning. In
1777, he reported that
acids are made when
sulphur, phosphorus or
carbon burn and the
products are dissolved
in water. He named the
gas in air that helps
things to burn ‘oxygen’,
meaning acid-former.
In 1838, Liebig
suggested that acids
are substances that
contain hydrogen, and
that this hydrogen is
released when acids
react with metals.
6
Justus von Liebig
(1803–1873)
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The nature of acids
3
Questions
1
a) Copy and correctly balance this symbol equation for Cavendish’s
‘inflammable air’ burning in air:
_H2 + O2 → _H2O
b) What is the modern name for ‘inflammable air’?
[1]
[1]
c) i)
Why did Cavendish think that water had been made in his experiment?
[1]
ii) Describe a simple chemical test that Cavendish could have done to prove
that water had been made.
[2]
[Total 5]
2
a) What is the modern name for the gas produced by Priestley in 1774?
[1]
b) Here is the symbol equation for the experiment carried out by Scheele:
MnO2 + 4HCl → MnCl2 + 2H2O + Cl2
i) What is the modern name for ‘muriatic acid’?
[1]
ii) The green-yellow gas was called ‘oxy-muriatic acid’. Did it contain oxygen
as its name suggests?
[1]
iii) Suggest why Priestley called the gas he made in 1772 ‘marine acid air’.
[1]
[Total 4]
3
Here are the formulae for acids made by Lavoisier: H2SO4, H3PO4 and H2CO3.
a) To what extent do his experiments with sulphur, phosphorus and carbon
show that all acids contain oxygen?
[1]
b) i) Apart from oxygen, which element do all three acids have in common?
[1]
ii) What compound is formed when this element burns in air?
[1]
iii) Suggest why Lavoisier might have been worried by Cavendish’s
experiment, and why he repeated it.
[2]
[Total 5]
4
a) Suggest why Scheele is given the credit for discovering chlorine, even though
he did not realise the reaction with muriatic acid produced an element.
[1]
b) Suggest how Lavoisier might have modified his theory of acids if he could
have known the results of Davy’s experiments on ‘oxy-muriatic acid’.
[2]
c) To what extent do the formulae of acids support Liebig’s suggestion that
acids are substances that contain hydrogen?
[1]
d) Cavendish thought that his ‘inflammable air’ came from the metals he used in
his experiments with acids. Was he right? Explain your answer.
[1]
e) Lavoisier gave hydrogen its name, meaning ‘water former’. Discuss whether
you think he got the names for oxygen and hydrogen the wrong way round.
[1]
[Total 6]
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SECTION
Questions and answers
3
What is the freezing point of pure
water in degrees Celsius?
0 °C
Why is chlorine added to drinking
water?
To kill bacteria
Name a gas responsible for
producing acid rain.
Sulphur dioxide
or nitrogen
dioxide
What happens when fertilisers run
off fields into rivers and lakes?
Algae grow
faster, oxygen is
used up, fish die
What happens to the temperature
of water as it boils?
It stays the same
What colour change happens when
water is added to dry cobalt
chloride paper?
Blue to pink
What is the source of energy
needed to drive the water cycle?
Heat from the
Sun
How can we get pure water from
sea water?
Use distillation
Name the main salt in sea water.
Sodium chloride
What is the reaction between an
acid and an alkali called?
Neutralisation
If a substance has a pH of 7, what
does that mean?
It is neutral
What does it mean if a substance
turns universal indicator paper red?
The substance is
strongly acidic
What do ammonia, toothpaste and
baking powder have in common?
They are all
alkalis
What will neutralise a wasp sting –
vinegar or baking soda?
Vinegar
What substances are formed when
an acid and alkali react together?
A salt and water
What substances form when an
acid reacts with a metal oxide?
A salt and water
What substances form when an
acid reacts with a metal carbonate?
A salt, water and
carbon dioxide
Name the salt formed when lithium
hydroxide reacts with sulphuric
acid.
Lithium sulphate
What acid should be used to make
ammonium nitrate?
Nitric acid
Describe a test for carbon dioxide.
Limewater turns
cloudy
Name the gas produced when
magnesium reacts with
hydrochloric acid.
Hydrogen
What is the chemical formula of
sulphuric acid?
H2SO4
Describe a simple laboratory test
for hydrogen.
A lighted splint
makes hydrogen
go ‘pop’
Name the industrial process used
to make sulphuric acid.
The Contact
Process
If a substance has a pH of 10, what
does that mean?
It is weakly
alkaline
What do we call a base that
dissolves in water?
An alkali
What happens to the pH of
hydrochloric acid when it is diluted
with water?
It goes up
Name the acid in the stomach.
Hydrochloric acid
What is the formula of water and
what does it tell us about the water
molecule?
H2O – it contains
two hydrogen
atoms and one
oxygen atom
Why are marble statues more
affected by acid rain than granite
ones?
Marble contains
calcium
carbonate which
reacts with acids;
granite does not
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SECTION
3
Water and solutions
Name
Date
PROGRESSION
Class
Tick the boxes that apply.
Or use traffic lights to show how confident you are (red = ‘I don’t know this’; orange = ‘I’m not
very confident about this’; green = ‘I’m confident I can do this’).
Level
At the end of the section
5
Safely carry out investigations involving distillation and
filtration.
5
Describe how distillation and filtration can be used to
separate simple mixtures.
5
Recall the melting and boiling points of water, and
describe the effects of dissolved impurities of these
temperatures.
5
Safely carry out investigations involving dilute acids
and alkalis.
5
Identify and explain the meaning of the hazard symbols
associated with acids and bases, including those for
corrosive, harmful and toxic.
5
Explain the choice of apparatus for investigations such
as the neutralisation reaction between acids and
alkalis, and the production of a salt.
5
Draw line graphs to present the results of a
neutralisation investigation, interpret the data and draw
conclusions from them.
5
Use indicators and pH numbers to classify solutions as
strongly acidic, weakly acidic, neutral, weakly alkaline
and strongly alkaline.
5
Explain how acid rain is caused, and describe some of
its effects on the environment.
6
Describe how to control the risks of working with acids
and alkalis.
6
Identify the variables involved in an investigation,
including the independent variable, the dependent
variable and control variables.
6
Describe and explain what happens to pH during a
neutralisation reaction.
6
Suggest how to improve an investigation, and give
suitable reasons for these suggestions.
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I need more
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Water and solutions
Level
At the end of the section
6
Explain some common uses of neutralisation reactions.
6
Recall the products formed when acids react with
metal hydroxides, metal oxides and metal carbonates.
6
Write word equations for the reactions between some
common acids and bases.
6
Recall ways in which the problems of acid rain can be
reduced.
7
Describe water in terms of its chemical formula and the
elements it contains.
7
Order and describe the main stages in the water cycle.
7
Describe how water from reservoirs is treated so that it
becomes safe to drink.
7
Explain the impact on living things of water pollution
from farms, factories, sewage and industrial accidents.
7
Link the hazards presented by an acid or alkali to its
pH value.
7
Describe and explain the temperature changes
observed when water is heated until it boils.
7
Give reasons for and against measures to control
emissions of sulphur dioxide.
8
Identify a suitable combination of acid and base to
produce a particular salt.
8
Write the chemical formulae of some common acids
and bases.
8
Write balanced symbol equations for the reactions
between some common acids and bases.
8
Discuss how the work of Joseph Black led to a change
in our understanding of reactions involving gases, in
particular air and carbon dioxide.
8
Describe how the hazards involved the manufacture of
sulphuric acid are controlled to maintain health and
safety and to protect the environment.
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3
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SECTION
3
Water and solutions
Name
Date
PROGRESSION
Class
Tick the boxes that apply.
Or use traffic lights to show how confident you are (red = ‘I don’t know this’; orange = ‘I’m not
very confident about this’; green = ‘I’m confident I can do this’).
Level
At the end of the section
I can
do this
I need more
work on this
Safely carry out investigations involving distillation and
filtration.
Describe how distillation and filtration can be used to
separate simple mixtures.
Recall the melting and boiling points of water, and
describe the effects of dissolved impurities of these
temperatures.
Safely carry out investigations involving dilute acids
and alkalis.
Identify and explain the meaning of the hazard symbols
associated with acids and bases, including those for
corrosive, harmful and toxic.
Explain the choice of apparatus for investigations such
as the neutralisation reaction between acids and
alkalis, and the production of a salt.
Draw line graphs to present the results of a
neutralisation investigation, interpret the data and draw
conclusions from them.
Use indicators and pH numbers to classify solutions as
strongly acidic, weakly acidic, neutral, weakly alkaline
and strongly alkaline.
Explain how acid rain is caused, and describe some of
its effects on the environment.
Describe how to control the risks of working with acids
and alkalis.
Identify the variables involved in an investigation,
including the independent variable, the dependent
variable and control variables.
Describe and explain what happens to pH during a
neutralisation reaction.
Suggest how to improve an investigation, and give
suitable reasons for these suggestions.
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Water and solutions
Level
At the end of the section
I can
do this
3
I need more
work on this
Explain some common uses of neutralisation reactions.
Recall the products formed when acids react with
metal hydroxides, metal oxides and metal carbonates.
Write word equations for the reactions between some
common acids and bases.
Recall ways in which the problems of acid rain can be
reduced.
Describe water in terms of its chemical formula and the
elements it contains.
Order and describe the main stages in the water cycle.
Describe how water from reservoirs is treated so that it
becomes safe to drink.
Explain the impact on living things of water pollution
from farms, factories, sewage and industrial accidents.
Link the hazards presented by an acid or alkali to its
pH value.
Describe and explain the temperature changes
observed when water is heated until it boils.
Give reasons for and against measures to control
emissions of sulphur dioxide.
Identify a suitable combination of acid and base to
produce a particular salt.
Write the chemical formulae of some common acids
and bases.
Write balanced symbol equations for the reactions
between some common acids and bases.
Discuss how the work of Joseph Black led to a change
in our understanding of reactions involving gases, in
particular air and carbon dioxide.
Describe how the hazards involved the manufacture of
sulphuric acid are controlled to maintain health and
safety and to protect the environment.
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Page 2 of 2
SECTION
3
End of section test
Name
1
Date
HIGHER
Class
a) What is meant by the term ’pure water’?
________________________________________________________________
[1]
b) Describe one simple chemical test for the presence of water.
________________________________________________________________
________________________________________________________________
[2]
c) The graph shows how the temperature of pure ice changes as it is heated
from −5 °C.
i)
Which point on the graph (A, C or E) represents liquid water? ___________
[1]
ii) What are the temperatures B and D?
Temperature B is ________ °C
Temperature D is ________ °C
[1]
d) i) What effect does dissolving salt have on the freezing point of water?
___________________________________________________________
[1]
ii) What effect does dissolving salt have on the boiling point of water?
_____________________________________________________________
[1]
[Total 7]
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End of section test
2
3
a) i) Explain how drinking water is chlorinated.
____________________________________________________________
[1]
ii) Explain why drinking water is chlorinated.
_____________________________________________________________
[1]
b) Why is there a small amount of residue when tap water is evaporated to dryness
but a larger amount after the same volume of sea water is evaporated to dryness?
________________________________________________________________
[1]
c) When some fossil fuels are burned in air, sulphur dioxide is formed. This gas
causes ‘acid rain’. Describe one way in which the amount of sulphur dioxide in
the air can be reduced.
________________________________________________________________
[1]
[Total 4]
3
Nathif investigated several substances to discover their effects on universal indicator.
a) The indicator solution changed from green to orange when mixed with vinegar.
i)
What does the green colour tell you about the universal indicator solution?
_____________________________________________________________
[1]
ii) What does the colour change tell you about vinegar?
_____________________________________________________________
[1]
b) Sodium hydroxide solution is strongly alkaline. What would be the colour
produced when universal indicator is added to sodium hydroxide solution?
________________________________________________________________
[1]
[Total 3]
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End of section test
4
3
Kathryn decided to investigate what happens when an alkali is added to an acid. She put
25 cm3 of acid into a beaker and then added 50 cm3 of alkali, 5 cm3 at a time. She
measured the pH of the mixture after each addition of alkali. The table shows Kathryn’s
results.
Total volume of
alkali added (cm3)
0
5
10
15
20
25
30
35
40
45
50
pH of the mixture
3.0
4.2
4.6
4.9
5.4
8.6
11.7
11.9
12.0
12.1
12.2
a) Suggest how Kathryn could measure the pH to the precision shown.
________________________________________________________________
[1]
b) Kathryn was concerned that her results might not be reliable.
i)
How could she improve the reliability of her results?
___________________________________________________________
[1]
ii) How could she check the reliability of her results?
_____________________________________________________________
[1]
c) Which is stronger, the acid or the alkali? Explain your answer.
________________________________________________________________
________________________________________________________________
[2]
[Total 5]
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End of section test
5
3
The instructions for preparing dry crystals of a particular salt have become muddled up.
a) Write the numbers 2, 3, 4, 5, and 6 in the spaces below to put the instructions in
the correct order.
Step
1
[2]
Instructions
Put 15 cm3 of dilute sulphuric acid in a test tube
Transfer the filtrate to an evaporating basin
Put the test tube in a hot water bath
Leave the solution so that the water can evaporate
Filter the mixture
Add small portions of copper oxide powder until the mixture stays cloudy
7
Examine the copper sulphate crystals
b) Why must the mixture be filtered?
________________________________________________________________
[1]
c) Complete the word equation below:
sulphuric acid + copper oxide → _________________ + _________________
[2]
d) Copper oxide is a base. Is it also an alkali? Explain your answer.
________________________________________________________________
________________________________________________________________
[1]
[Total 6]
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SECTION
3
End of section test
Name
1
Date
EXTENSION
Class
Kathryn put 25 cm3 of acid into a beaker and then added 50 cm3 of alkali, 5 cm3 at a
time. She measured the pH of the mixture after each addition of alkali. The table shows
her results.
Total volume of
alkali added (cm3)
0
5
10
15
20
25
30
35
40
45
50
pH of the mixture
3.0
4.2
4.6
4.9
5.4
8.6
11.7
11.9
12.0
12.1
12.2
a) Why did the pH of the mixture increase during the experiment?
________________________________________________________________
[1]
b) Which is stronger, the acid or the alkali? Explain your answer.
________________________________________________________________
________________________________________________________________
[2]
c) Complete the word equation below:
hydrochloric acid + sodium hydroxide → ______________ + _______________
[2]
d) Name the gas given off when acids react with metals.
________________________________________________________________
[1]
[Total 6]
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End of section test
2
3
Potassium nitrate is used in fertilisers. ‘Low salt’ products contain potassium chloride.
a) Name the acid needed to produce potassium nitrate.
________________________________________________________________
[1]
b) Name a base used to make potassium chloride and potassium nitrate.
________________________________________________________________
[1]
c) What happens to an acid when a base is added to it?
________________________________________________________________
[1]
[Total 3]
3
The names and chemical formulae of six compounds are shown in the table.
Name
Formula
Name
Formula
ammonia
NH3
potassium sulphate
K2SO4
ammonium phosphate
(NH4)3PO4
phosphoric acid
H3PO4
potassium hydroxide
NaOH
sulphuric acid
H2SO4
a) Phosphoric acid reacts with ammonia to form ammonium phosphate.
Balance the symbol equation below for the reaction:
H3PO4 +
NH3 →
(NH4)3PO4
[1]
b) Sulphuric acid reacts with potassium hydroxide.
Complete and then balance the symbol equation below for the reaction:
H2SO4 +
KOH → ______________ + ______________
[3]
[Total 4]
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End of section test
4
3
Hannah wanted to try some of Joseph Black’s experiments from the 18th century.
a) She weighed exactly 1.00 g of calcium carbonate, and then heated it strongly for
ten minutes. The symbol equation for the reaction is:
CaCO3 → CaO + CO2
She weighed the residue after it had cooled and found that its mass was 0.56 g.
i)
Why did the mass decrease?
_____________________________________________________________
[1]
ii) She heated the residue for a second time then let it cool. Why did the mass
stay at 0.56 g when she heated the residue again?
_____________________________________________________________
[1]
b) She weighed another 1.00 g of calcium carbonate, and then mixed it with 10 g of
hydrochloric acid. The symbol equation for the reaction is:
CaCO3 + 2HCl → CaCl2 + H2O + CO2
i)
Hannah had added enough acid to react with all the solid. What was the total
mass of the solid and acid after the reaction? Show your working out.
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
[2]
ii) Explain your answer to part (i)
_____________________________________________________________
_____________________________________________________________
[2]
[Total 6]
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End of section test
5
3
Steve wanted to see if the mass of dissolved salt affects the boiling point of water.
a) Write a plan for Steve’s investigation, which uses ordinary laboratory equipment.
Your plan must:
• identify the independent variable and the dependent variable
• identify a control variable
• include a brief description of how to do the experiment.
[4]
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
__________________________________________________________________
b) Make a table that Steve could use to record his results in the space below.
[2]
[Total 6]
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SECTION
End of section mark scheme
3
Higher tier (equivalent to NC levels 5 and 6)
Question
Answer
Mark scheme
b
Water with nothing else mixed or dissolved
in it
Anhydrous copper sulphate crystals turn
from white to blue
Cobalt chloride paper turns from blue to pink
c i
ii
C
B is 0 °C; D is 100 °C
1 mark – or any
equivalent answer
1 mark for correct
substance
1 mark for correct
colour change
1 mark
1 mark – need
both
1 mark
1 mark
1 mark
1 mark
1 mark – or any
equivalent answer
1 a
d i
ii
2 a i
ii
b
c
3 a i
ii
b
4 a
b i
ii
c
5 a
Decreases the freezing point
Increases the boiling point
Chlorine gas is bubbled through the water
To kill bacteria / harmful microorganisms
Tap water contains a small amount of
dissolved substances; sea water contains a
lot of dissolved substances
Burn less fossil fuels / remove sulphur from
fossil fuels before they are burned / remove
sulphur dioxide from flue gases
It is neutral / its pH is 7
It is a weak acid / it is weakly acidic
dark blue / purple / violet
Use a pH meter
Repeat her experiment
Compare her results with another group
The alkali
When equal volumes had been mixed, the
pH was higher than 7
5
Transfer ... evaporating basin
2
Put the ... water bath
6
Leave the ... evaporate
4
Filter the mixture
3
Add small ... stays cloudy
b
c
To remove unreacted copper oxide
copper sulphate; water
d
No – it is insoluble in water
NC level
(optional)
5
5
6
6
6
6
5
5
5
1 mark
5
1 mark
1 mark – must
refer to weak acid
1 mark
1 mark
1 mark
1 mark
1 mark
1 mark
5
5
2 marks for all
steps in correct
order
1 mark if three
steps are in
correct order
1 mark
1 mark each,
either order
Answer and
reason needed for
1 mark
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5
5
6
6
6
6
6
6
6
Page 1 of 2
End of section mark scheme
3
Extension tier (equivalent to NC levels 6, 7 and 8)
Question
1 a
b
c
d
2 a
b
c
3 a
b
4 a i
ii
b i
ii
5 a
b
Answer
Mark scheme
The alkali neutralised the acid / alkalis have
high pH values
The alkali
When equal volumes of alkali and acid had
been mixed, pH was higher than 7
water
sodium chloride
hydrogen
1 mark
NC level
(optional)
6
1 mark
1 mark
6
1 mark
1 mark
1 mark
6
6
nitric acid
1 mark
7
potassium oxide / potassium hydroxide /
potassium carbonate
It is neutralised
1 mark
7
1 mark
7
H3PO4 + 3NH3 → (NH4)3PO4
1 mark
8
H2SO4 + 2KOH → K2SO4 + 2H2O
or
H2SO4 + KOH → KHSO4 + H2O
1 mark for each
correct product
1 mark for
balancing
1 mark
8
8
1 mark
8
1 mark
1 mark
1 mark
1 mark
8
1 mark – ½ mark
for each variable
1 mark
1 mark
7
Carbon dioxide was given off
All the calcium carbonate had decomposed /
calcium oxide does not decompose when it
is heated
e.g. 1.00 + 10.00 – 0.44
= 10.56 g
Carbon dioxide was lost in both reactions.
The same mass of calcium carbonate would
release the same mass of gas
Independent variable: mass of salt
Dependent variable: boiling point
Control variable: volume of water
Simple workable method that includes at
least three key pieces of apparatus, such as
balance, Bunsen burner, measuring cylinder,
thermometer.
Reference to safety steps taken
Table with columns/rows labelled for mass of
salt added and boiling temperature
Both headings labelled with units
1 mark
1 mark
8
7
1 mark
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SECTION
3
Question bank
Name
1
Date
Class
The table shows estimates for the annual amount of evaporation and precipitation (rain,
hail and snow) that happens in the Earth’s water cycle.
Over oceans Over the land
Evaporation (trillions of tonnes per year)
428
72
Precipitation (trillions of tonnes per year)
391
109
a) Draw a suitable chart to show the information in the table.
[2]
b) i) Calculate the total annual amount of evaporation in a year.
____________________________________________________________
[1]
ii) Calculate the total annual amount of precipitation in a year.
_____________________________________________________________
[1]
iii) Compare your answers to parts (i) and (ii). Explain what you notice.
_____________________________________________________________
_____________________________________________________________
[1]
c) What is the source of the energy that drives the water cycle? _______________
[1]
d) What percentage of total evaporation happens over the oceans? Suggest why
this is so.
___________________________________________________________
___________________________________________________________
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[1]
Page 1 of 3
Question bank
3
e) Explain why the figures in the table are estimates, and may vary according to
which team of scientists has worked on the problem.
___________________________________________________________
___________________________________________________________
___________________________________________________________
[1]
[Total 8]
2
Abrar found a bottle of a clear, colourless liquid. He thought it was pure water, but its
label was missing.
a) Describe what he would see if the liquid was pure water and he added it to:
i)
anhydrous copper sulphate crystals _______________________________
[1]
ii) dry cobalt chloride paper ________________________________________
[1]
b) The tests described in part (a) would not prove that the liquid was pure water.
Describe a physical test that Abrar should carry out to see if the liquid was pure
water. Explain the results he should get for pure water.
______________________________________________________________
______________________________________________________________
______________________________________________________________
[3]
[Total 5]
3
Chemists can use indicators to distinguish between acidic, neutral and alkaline solutions.
Universal indicator and litmus are not the only indicators. The table shows the colours at
different pH values of two other indicators – phenolphthalein and thymol blue.
pH value
Indicator
1
universal indicator
2
red
litmus
3
4
5
orange
6
yellow
red
phenolphthalein
thymol blue
green
purple
colourless
red
7
yellow
8
blue
9
10
11
violet
blue
pink
blue
a) Jenny tested different substances with different indicators. Identify the colours she
would see for:
i)
a neutral solution with litmus ____________________________________
[1]
ii) a strongly alkaline solution with phenolphthalein _____________________
[1]
iii) a weakly acidic solution with thymol blue ___________________________
[1]
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Question bank
3
b) Suggest why phenolphthalein is less useful than thymol blue as an indicator
when analysing acids.
___________________________________________________________
[1]
c) Suggest why universal indicator is used so often compared to the other ones.
___________________________________________________________
___________________________________________________________
[2]
[Total 6]
4
Stomach acid is hydrochloric acid. One cause of indigestion is the presence of too much
of this acid. Antacids are medicines that people can swallow to neutralise some of the
stomach acid, and so relieve the symptoms.
a) ‘Milk of Magnesia’ is an antacid containing magnesium hydroxide.
i)
Write a word equation for the reaction when Milk of Magnesia is swallowed.
___________________________________________________________
[1]
ii) Suggest why sodium hydroxide is not used in indigestion remedies.
___________________________________________________________
[1]
b) Some antacids contain calcium carbonate rather than magnesium hydroxide.
i)
Name the salts formed when these antacids react with hydrochloric acid.
___________________________________________________________
[1]
ii) Suggest one side-effect of swallowing an antacid tablet that contains calcium
carbonate.
___________________________________________________________
[1]
iii) Write a balanced symbol equation for the reaction.
___________________________________________________________
[2]
[Total 6]
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SECTION
Question bank mark scheme
Question
1 a
b i
ii
iii
Answer
Appropriate graph (e.g. bar chart) with sensible
scales and labelled axis
Bars plotted correctly and identified
428 + 72 = 500 trillion tonnes
391 + 109 = 500 trillion tonnes
The amounts are the same / the water is being
driven around the water cycle
c
d
Heat (thermal) energy from the Sun
(428 ÷ 500) × 100 = 85.6 %
Most of the Earth is covered by oceans
e
Sensible suggestion – e.g. different scientists
may use different methods
Colour change from white to blue
2 a i
ii
b
3 a i
ii
iii
b
c
4 a i
ii
b i
ii
iii
Colour change from blue to pink
Description of how to measure melting and
boiling points of water – e.g. heat ice up, take
temperature at regular intervals until boiling
Temperatures should be 0 °C and 100 °C
purple
pink
yellow
Thymol blue distinguishes weak acids from
strong ones, unlike phenolphthalein
Greater range of colours
Greater range of pH values identified
hydrochloric acid + magnesium hydroxide →
magnesium chloride + water
strong alkali / corrosive
calcium chloride
wind, burping
2HCl + CaCO3 → CaCl2 + H2O + CO2
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This document may have been altered from the original
Mark scheme
1 mark
1 mark
1 mark
1 mark
1 mark
(explanation
needed)
1 mark
1 mark for
calculation and
reason
1 mark
1 mark (both
colours)
1 mark (both
colours)
1 mark for
sensible
method, 1 mark
for explaining
results
1 mark for both
1 mark
1 mark
1 mark
1 mark
1 mark
1 mark
1 mark
1 mark
1 mark
1 mark
1 mark for
formulae
1 mark for
balancing
3
NC level
(optional)
5
5
5
6
6
7
8
5
5
7
5
6
6
7
7
6
6
6
7
8
Page 1 of 1
SECTION
3
Answers
Topic 3.1 Quick check questions
iii) Evaporation occurs when the water in the
sea, rivers and lakes is heated and turns into a
gas [1]
iv) Melting occurs as the snow and ice is heated
and turns into a liquid [1]
[Total 8]
a) reservoir [1]
b) filtration [1]
c) chlorine [1]
[Total 3]
Labelled diagram including evaporating basin ½];
tripod stand [½]; Bunsen burner [½]; tap water ½]
[Total 2]
a) Title [1]; labels on axes [1 ]; scale and
units/names on each axis [1 ]; accurately drawn
[1]
b) Washing ourselves [1]
c) 160 litres [1]
d) 25% [1]
[Total 7]
Each source [4 × ½]; each threat [4 × ½]
[Total 4]
sodium chloride; magnesium; calcium;
potassium; iodine etc. [½ each max. 2] [Total 2]
1 A – water being heated; particles move about
faster in the liquid; temperature is rising [1]
B – water being heated, particles move about as
fast as they can in the liquid; temperature has
risen to the boiling point of water [1]
C – water is heated to its boiling point,
temperature does not rise anymore; additional
energy makes particles leave the liquid and
become a gas [1]
D – water being cooled; particles move slower in
the liquid; temperature is falling [1]
E – water cooled to its freezing point; the liquid
starts to change into a solid as particles start to
become fixed in position and don’t move over
each other [1]
F – all the water has changed into solid (ice); as
it cools further the temperature falls further;
particles vibrate slower and slower [1]
2 freezing [1] – ice forming;
condensation [1] – clouds forming;
evaporation [1] – puddles drying up;
[1] for descriptions
3 River water contains germs [1] and solid
particles [1]
4 Rivers in city could contain pollution from
factories and houses, fuels, detergents, etc.
River in the countryside could contain pollution
from farming, fertilisers, etc. [Any 3]
5 Put some in an evaporating basin and heat it to
evaporate the water [1]; any impurities will be left
in the evaporating basin [1]
7
Topic 3.1 Questions
Topic 3.2 Questions
1 Water is a compound of oxygen [½] and
hydrogen [½]. The formula of water is H2O [½]
We can test for water by using cobalt chloride
paper which changes from blue [½] to pink [½]
Water boils at 100 °C [½] and melts at 0 °C [½].
Impurities raise [½] the boiling point of water.
[Total 4]
2 Any suitable phrase to explain words – e.g.
a) The water cycle shows the changes of state of
water in nature [1]
b) Condensation of water in the upper
atmosphere to form water droplets leads to cloud
formation [1]
[Total 2]
3 a) 1 Sun [½]; 2 sea [½]; 3 clouds [½]; 4 rain [½];
5 mountain [½]; 6 snow [½]; 7 river [½]; 8 lake
[½]
[Total 4]
b) Suitable sentences including words – e.g.
i) Condensation occurs in the upper atmosphere
[1]
ii) Freezing occurs high up where the
temperatures falls below the freezing point of
water [1]
4
5
6
8
Topic 3.2 Quick check questions
1 Substance that changes colour depending on the
type of solution [1]
2 It can damage skin and metals [1]
3 a) blue/purple [1]
b) red/orange [1]
c) green [1]
d) blue/purple [1]
4 Orange juice is already coloured [1]
5 Rises towards 7 [1]
6 From red to orange to yellow to green [1]
1 Acids have a pH that is less [½] than 7 and turn
universal indicator orange [½] or red [½].
Alkalis have a pH that is more [½] than 7 and
turn universal indicator blue [½] or purple [½]
[Total 3]
2 One suitable sentence for each of the following
words – e.g.
a) Neutralisation occurs when an acid cancels
out an alkali to form a neutral solution [1]
b) Solution with a pH less than 7 is an acid [1]
c) An indicator changes colour in acids and
alkalis [1]
d) The pH scale is a measure of how acid or
alkaline a solution is [1]
[Total 4]
3 a) E [1]
b) D [1]
c) A [1]
d) A, B and C [2]
[Total 5]
4 E.g. The nettle sting is acidic so rubbing with an
alkali [1] will neutralise [1] the acid [1] and relieve
the sting
[Total 3]
5 a) Measure volume of acid [½] using syringe [½]
etc. into beaker. Add indicator [½]. Add acid [½]
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Page 1 of 5
Answers
using syringe [½] etc. until indicator shows
neutral [½]
b) Indicator would go green [1]
c) Wear safety glasses [1] and wash any
splashes immediately [1]
[Total 7]
d) 25 cm3 [1]
Topic 3.3 Quick check questions
1 salt and water are formed [1]
2 Dissolved in the water [1]
3 By using an indicator [1] and adding the acid
slowly until the indicator shows the solution is
neutral [1]
4 nitric acid + sodium hydroxide → sodium nitrate
+ water [2]
5 a) nitric acid + lead oxide → lead nitrate + water
[2]
b) sulphuric acid + sodium carbonate → sodium
sulphate+ water + carbon dioxide [2]
6 Substance which neutralises an acid forming a
salt and water [1]
7 A base can be soluble or insoluble in water – an
alkali is soluble in water [1]
8 Contains dissolved carbon dioxide [1]
Topic 3.3 Questions
1 When an acid [½] reacts with a base we say a
neutralisation [½] reaction has occurred.
Neutralisation reactions always produce a salt
[½] and water [½]
[Total 2]
2 a) sulphuric acid [1]
b) hydrochloric acid [1]
c) nitric acid [1]
[Total 3]
3 Hydrogen [1]; lighted splint [1] pops [1]
Carbon dioxide [1]; limewater [1] goes milky [1]
[Total 6]
4 Suitable sentence containing each pair of words
a) An acid reacts with a metal oxide [1] to form a
salt and water [1]
b) An acid reacts with a metal carbonate [1] to
form a salt, carbon dioxide and water [1]
[Total 4]
5 a) sulphuric acid + magnesium → magnesium
sulphate [1] + hydrogen [1]
b) nitric acid [1] + potassium hydroxide →
potassium nitrate + water [1]
c) copper carbonate + hydrochloric acid →
copper chloride [1] + water [1] + carbon dioxide
[1]
d) zinc oxide [1] + phosphoric acid [1] → zinc
phosphate + water
[Total 9]
6 a) cobalt oxide/hydroxide/carbonate [1] +
hydrochloric acid [1]
b) iron oxide/hydroxide/carbonate [1] + sulphuric
acid [1]
c) zinc oxide/hydroxide/carbonate [1] + nitric acid
[1]
[Total 6]
3
7 Each word in correct context – e.g.
When an acid [1] reacts with an alkali [1] the
main product [1] is a salt [1]
[Total 4]
8 a) Less air pollution (from burning fuels) [1]
b) An alkali [1]
c) No – it will always contain some carbon
dioxide from our atmosphere [1]
[Total 3]
9 a) carbon dioxide [1]
b) Stops fizzing [1]
c) zinc chloride [1]
d) effervescence [1]; neutralisation [1]
e) filter funnel [½]; filter paper [½]; name the
residue [½]] and filtrate [½]
[Total 7]
10Put small amount of each in different test tubes.
Add a piece of magnesium to each.
The one that fizzes is hydrochloric acid [2]
Wash out the test tubes and put some of the two
unknown solutions in different test tubes.
Add some hydrochloric acid to each.
The one that fizzes is potassium carbonate. [2]
The other is sodium hydroxide. [2]
You should wear safety glasses and wash spills
with water [1]
[Total 7]
HSW Topic 3.4 The scientific method
Quick check questions
1 An educated guess at an answer to a question
[1]
2 An idea about why things happens – it tries to
explain the facts [2]
3 Heating magnesia alba [1]; adding sulphuric acid
to magnesia alba[1]; the manufacture of
alcohol[1]; burning charcoal[1]; and by
respiration[1]
Questions
1 Hypothesis – educated guess based on
experiences in other areas [2]
Conclusion – description of what happens based
on observations made during experiments [2]
[Total 4]
2 a) He presented a lecture to the Philosophical
Society of Edinburgh [1]
b) He might have use video conferencing or
published on the internet [2]
c) Other scientists would carry out experiments
to see if they could get the same results [2]
[Total 5]
3 a) Priestley and Lavoisier [2]
b) Importance of careful measurement [1]
[Total 3]
4 a) calcium carbonate → calcium oxide + carbon
dioxide [2 − ½ each mistake]
b) calcium oxide + carbon dioxide → calcium
carbonate [2 − ½ each mistake]
[Total 4]
5 Labelled diagram showing flask [1] containing
magnesium carbonate and sulphuric acid[1],
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delivery tube to trough [1] with upturned test tube
full of water[1] and gas bubbling into test tube [1]
[Total 5]
6 Thinking about a question [1]
Research into the problem [1]
Planning and carrying out experiments [1]
Analysing the results [1]
Making the results and conclusions available to
other scientists [1]
[Total 5]
HSW Topic 3.4 The chemical industry
Quick check questions
1 It improves our standards of living, creates
wealth (exports) and creates jobs [2]
2 Health and safety (control of hazardous
substances) [1]; the effect on the local
environment [1]
3 fertilisers [1]
4 Control of Substances Hazardous to Health [1]
Questions
1 a) The Contact process [1]; sulphur [1], air [1],
water [1]
b) sulphur + oxygen [1] → sulphur dioxide [1]
sulphur dioxide + oxygen [1] sulphur trioxide
[1]
[Total 8]
2 a) 98% [2]
b) wear eye protection [1]; gloves [1]; keep away
from mouth [1]; it is corrosive and toxic [1]
[Total 6]
3 a) Availability of trained workers [1]; availability
of water [1]; sulphur distance to markets [1];
pollution of local area [1]; safety procedures for
workforce [1]
b) employment [1]; associated industries [1]
c) Possible pollution problems [1]; increased
traffic on roads [1]
[Total 9]
4 Any five of labourers, cleaners, store men, plant
operators, chemists, lorry drivers, office staff,
sales, marketing community liaison, etc. [Total 5]
5 Labels on each axis [1]; scale and units/names
on each axis [1]; accurately drawn [1] [Total 3]
End of Section 3 questions
1 a)
[1]; H2O [1]
3
c) 585 million litres [1]
d) 10500 [1]
e) flushing toilets [½] and washing [½] [Total 5]
4 They could use presentations at conferences,
articles in magazines or the internet [3]
They need to communicate their findings so that
others can check their results and conclusions
[1]
[Total 4]
5 nitric acid at pH < 2 [1]; bleach ~ 5 [1];
sugar = 7 [1]; sodium hydroxide >12 [1] [Total 4]
6 Acids
Alkalis
Neutrals [1]
vinegar
orange juice
tea
battery fluid
bleach
toothpaste
oven cleaner
water
salt
sugar
alcohol
indig. remedies
[2]
[2]
[2]
[Total 7]
7 a) rises [1]
b) falls[1]
c) rises[1]
d) stays the same [1]
[Total 4]
8 a) magnesium + ethanoic acid [1] → magnesium
ethanoate + hydrogen [1]
b) sodium carbonate + ethanoic acid [1] →
sodium ethanoate + water + carbon dioxide [1]
c) iron oxide + ethanoic acid [1] → iron
ethanoate + water [1]
[Total 6]
9 a) sulphuric acid + sodium hydroxide → sodium
sulphate [1] + water [1]
b) nitric acid [1] + magnesium [1] → magnesium
nitrate + hydrogen
c) zinc oxide + hydrochloric acid [1] → zinc
chloride + water [1]
d) phosphoric acid + sodium carbonate →
sodium phosphate [1] + water [1] + carbon
dioxide [1]
[Total 9]
10Bicarbonate alkaline [1]; for acidic bee stings [1]
Vinegar acidic [1]; for alkaline wasp stings [1]
[Total 4]
11Add excess [½] nickel carbonate [1] to
hydrochloric acid [1]
Filter [1] the excess nickel carbonate [½]
evaporate [½] half of the water [½]
Leave to evaporate [½] to form nickel chloride
crystals [½]
[Total 6]
12a) acidic [1]
b) neutralisation [1]
c) salt [1]
d) calcium carbonate [1]
[Total 4]
b) ½ mark for each of the following terms
correctly used: Sun; heat; evaporation; higher;
cools; condensation; water; droplets; cloud [4]
[Total 6]
2 Add indicator [½]; red/orange acid [1]; green
neutral [½]; blue purple alkali [1]
[Total 3]
3 a) 19500 million litres [1]
b) 336.2 litres [1]
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Topic worksheets
3.1 Our water supply
1 Suitably labelled flow chart including (screen) [1];
settling [1]; filtering [1]; chlorination [1]; storage
[1]; piping [1]; with appropriate text
2 a) Bar chart [1]; sensible scales [1]; labelled axes
[1]; correctly plotted [1]
b) i) Food preparation and drinking [1]
Because it is swallowed [1]
ii) flushing toilet, garden, car [1]
Water is not swallowed [1]
iii) bath, shower, dishwasher, laundry [1]
Water might be swallowed or in contact with skin
[1]
c) i) Stage identified [1]; sensible reasons [1]
ii) Two or more sensible suggestions – e.g.
limited resource, reduction in energy or
chemicals [2]
3.2 Answers – not questions
Pupil’s own suggestions – 1 mark for each sensible
correct question per answer
3.3 Making salts
1 Jigsaws assembled correctly, 1 mark each [8]
2 1 mark for each correct word equation [12]
HSW worksheets
Chlorination of drinking water
1 a) hydrochloric acid [1]; chloric acid [1]
b) chloric acid [1]
c) Low pH values ensure a higher concentration
of chloric acid [1]
d) Lower pH might be harmful / pH 7.3 is close to
neutral [1]
2 a) Any sensible answer – e.g. it is enough to kill
microorganisms [1]
b) i) It is just a bit less than concentration at
which consumers complain [1]
ii) Sensible reasons explained – e.g. chlorine is a
gas so it will escape [1]; chlorine reacts with
other chemicals in water so amount is reduced
[1]
c) Sensible reason explained – e.g. need to be
sure that microorganisms are killed [1]; people
are not going to drink it [1]
3 Benefits outweigh the risk [1]. Discussion (to a
maximum of 3 marks) should include sensible
advantages (e.g. makes water safe to drink) and
sensible disadvantages (e.g. taste, smell, cost of
adding chlorine, etc.) [3]
3
Joseph Black and chalk
1 a) i) calcium chloride [1]; water [1]; carbon
dioxide [1]
ii) carbon dioxide [1]
iii) calcium chloride [1]; water [1]
b) He needed to make very accurate / precise
measurements to detect small changes in mass
[1]
c) Chalk is calcium carbonate [1]; quicklime is
calcium oxide [1]
2 a) To make it a fair test [1]
b) 1 mark for each of two sensible suggestions –
e.g. he got the same loss in mass in both
experiments / the loss in Experiment 1 was
caused by a gas (because of fizzing) / there was
no further loss of mass in Experiment 3 after the
gas had gone [2]
3 a) (Many) people breathed out carbon dioxide
[1]; turns limewater cloudy [1]
b) To check if it was something the people
produced that made the limewater go cloudy [1]
Sulphuric acid
1 a) £150 per tonne / 4 times [1]
b) fertiliser manufacture [1]; bioethanol [1]
2 a) + oxygen [1]
b) Sulphuric acid is made from sulphur [1]
c) Any two sensible reasons for 1 mark each –
e.g. cost of extraction, cost of transporting it,
increased demand, limited supplies, etc. [2]
3 a) Sugar beet must be grown, it needs fertilisers
[1]
b) Sulphuric acid is used in the manufacture of
fertilisers [1]; an increase in demand for
fertilisers increases demand for sulphuric acid [1]
c) Increase in demand for fertilisers [1]; increase
in demand for sulphuric acid for bioethanol
manufacture [2]
4 1 mark for a sensible reason – e.g. increased
price of sulphuric acid means that recycling
seems relatively less expensive [1]
1 mark for each suggestion to a maximum of 3:
advantages – e.g. saves resources, saves
energy; disadvantages – e.g. cost of collection or
transport, disposal of waste materials, etc. [3]
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2H3PO4 + 3MgCO3 → Mg3(PO4)2 + 3H2O + 3CO2
[1]
Extension worksheets
Symbol equations
1 1 mark for each correct name and formula [11]
hydrochloric acid
HCl
nitric acid
HNO3
Bases
sodium
hydroxide
NaOH
sodium
chloride
NaCl
sodium nitrate
NaNO3
sulphuric
acid
H2SO4
phosphoric acid
H3PO4
sodium
sulphate
Na2SO4
sodium
phosphate
Na3PO4
Acids
copper oxide
CuO
copper
chloride
CuCl2
copper nitrate
Cu(NO3)2
copper
sulphate
CuSO4
copper
phosphate
Cu3(PO4)2
3
magnesium
carbonate
MgCO3
magnesium
nitrate
Mg(NO3)2
magnesium
sulphate
MgSO4
magnesium
phosphate
Mg(PO)4
2 a) hydrochloric acid + sodium hydroxide →
sodium chloride + water [1]
hydrochloric acid + copper oxide → copper
chloride + water [1]
nitric acid + sodium hydroxide → sodium nitrate
+ water [1]
nitric acid + copper oxide → copper nitrate +
water [1]
nitric acid + magnesium carbonate →
magnesium nitrate + water + carbon dioxide [1]
sulphuric acid + sodium hydroxide → sodium
sulphate + water [1]
sulphuric acid + copper oxide → copper sulphate
+ water [1]
sulphuric acid + magnesium carbonate →
magnesium sulphate + water + carbon dioxide
[1]
phosphoric acid + sodium hydroxide → sodium
phosphate + water [1]
phosphoric acid + copper oxide → copper
phosphate + water [1]
phosphoric acid + magnesium carbonate →
magnesium phosphate + water + carbon dioxide
[1]
b) 1 mark for each equation for correctly writing
in formulae (see part c) [11]
c) HCl + NaOH → NaCl + H2O [1]
2HCl + CuO → CuCl2 + H2O [1]
HNO3 + NaOH → NaNO3 + H2O [1]
2HNO3 + CuO → Cu(NO3)2 + H2O [1]
2HNO3 + MgCO3 → Mg(NO3)2 + H2O + CO2 [1]
H2SO4 + 2NaOH → Na2SO4 + 2H2O [1]
H2SO4 + CuO → CuSO4 + H2O [1]
H2SO4 + MgCO3 → MgSO4 + H2O + CO2 [1]
H3PO4 + 3NaOH → Na3PO4 + 3H2O [1]
2H3PO4 + 3CuO → Cu3(PO4)2 + 3H2O [1]
The nature of acids
1 a) 2H2 + O2 → 2H2O [1]
b) hydrogen [1]
c) i) Dew formed [1]
ii) 1 mark for correct substance and 1 mark for
correct colour change – e.g. white anhydrous
copper sulphate [1] turns blue [1] / blue cobalt
chloride paper turns pink
2 a) oxygen [1]
b) i) hydrochloric acid [1]
ii) No [1]
iii) He made it from sodium chloride, which is
found in sea water [1]
3 a) All three produced acids containing oxygen [1]
b) i) hydrogen [1]
ii) water [1]
iii) water is not an acid (it is neutral) [1]; this is an
exception to his idea [1]
4 a) He was the first person to make it [1]
b) He might have said that acids contain
hydrogen [1]; Davy showed that hydrochloric
acid did not contain oxygen [1]
c) They contain H for hydrogen [1]
d) No – it came from acids [1]
e) Oxygen does not always form acids, but acids
contain hydrogen [1]
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