MAKING CLEAR
SOUP
INVESTIGATING
SOLUBILITY
5-14 Environmental Studies, Science,
Levels E and F
National Curriculum, Key Stage 3
MAKING CLEAR SOUP
Investigating Solubility
Secondary:
Making Clear Soup. Investigating solubility:
This web based resource is written for 5-14 Environmental Studies, Science,
Levels E and F in Scotland and for the National; Curriculum, Key Stage 3, in
England and Wales. It includes many practical activities and background
information for these levels. There are Teacher, Technician and Pupil
sheets available. All the activities are freely available via the SAPS web
site: saps.org.uk
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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MAKING CLEAR SOUP
Investigating Solubility
Acknowledgements:
The authors, Pam Ferguson and Marjorie Smith, would like to thank the
following for their involvement with this work.
ICI, in particular, Jane Gamble, formerly Education Officer
for ICI.
SAPS, Science and Plants for Schools
(http://www.saps.org.uk/)
Dollar Academy, particularly Cameron Smith of the Chemistry
Department and his classes, for allowing us to trial the topics.
(http://www.dollaracademy.org.uk/)
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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MAKING CLEAR SOUP
Investigating Solubility
CONTENTS
Introduction to Soups and Solutions.
Investigation work on salt solutions with follow up questions
Examination of prepared packets of soups. Analysis of ingredients.
Alternative investigation into dissolving.
Solutions, suspensions and colloidal dispersions with an investigation into
the properties of colloidal dispersions and solutions.
Factors affecting the rate of dissolving.
Background information for group work on rate of dissolving.
Workcard 1: The Temperature of the Water.
Workcard 2: The Amount of the Solute.
Workcard 3: Stirring and how much Stirring?
Workcard 4: The Volume of the Water Used.
Workcard 5: The Particle Size.
Workcard 6: Pupil defined factor.
Teacher Supplementary Notes: Alternative route for investigating
solubility.
Investigation to test the hypothesis that: The time required to cause a
change in temperature increases as the amount of material dissolved in
the water increases. The more the dissolved substance the less the
rise in temperature.
Examining the concept of controls in experiments.
Further related investigations and identifying variables.
Pupil booklet
Technical Guide: Materials and equipment for the learning and assessing
activities.
Glossary
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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MAKING CLEAR SOUP
Investigating Solubility
Making Clear Soup
Introduction to Soups and Solutions:
Many people like soup, especially when the days are cold and dark. In our
country more people prefer hearty, thick, creamy soups. In other countries
a clear soup is often the favourite. Soups are meant to stimulate the
appetite and get our digestion ready for the main course. A clear chicken
noodle soup is sometimes used to feed a sick person and some research
suggests that there may be ingredients in such a soup that helps to heal a
person suffering from a cold.
Your challenge is to help to design a soup that will satisfy the European
market for clear soup. You are going to look at many of the variables
involved in such a design. You will have to think about what ingredients could
go into the soup. If you have to keep it clear, you will need to look at
ingredients that dissolve into a solution.
What does dissolve mean?
What does solution mean?
When you add a spoonful of sugar to a cup of hot tea, it
dissolves and forms a sweet solution. This means the
sugar appears to dissappear from view. However, it is still
there because when you taste the tea, it tastes sweet.
A substance which dissolves to make a solution is said to
be soluble. A substance which does not dissolve is said to
be insoluble (e.g. sand). The substance which is dissolved
is called the solute ( e.g. sugar in this case). And the substance which does
the dissolving is called the solvent, (e.g. the hot water in the tea). Water is
the commonest solvent but there are many others, ( e.g. ethanol, hexane).
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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MAKING CLEAR SOUP
Investigating Solubility
Investigation work on salt solutions with follow up
questions.
How much salt will dissolve in 50 ml water?
Materials
Graduated cylinder
Beaker
Water
Salt ( about 25g on a small piece of
paper)
Stirring rod
Spatula
Balance
Method
 Prepare a table in your notebook like this:
Mass of salt and paper before
dissolving
Mass of salt and paper when no more
salt dissolves
Mass of salt that dissolved in 50 ml
water






g
g
g
Find the mass of the salt and paper, and record the mass in your table.
Measure 50 ml water into the graduated cylinder and then pour it into
the beaker.
Using the spatula, place a small amount of salt into the water and using
the stirring rod, stir to dissolve.
When the salt has completely dissolved, continue
adding a small quantity of salt, stirring until
dissolved. Look for traces of undissolved salt in
the water. Eventually you will find that the salt
in the bottom will not dissolve, no matter how
much you continue to stir it.
When no more salt will dissolve, measure the
mass of the salt that remains on the paper.
Record this amount.
Calculate the mass of the salt that dissolved.
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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MAKING CLEAR SOUP
Investigating Solubility
Questions:
1. Was there a limit to how much solute would dissolve?
2. How much salt dissolved in the 50 ml of water?
3. Try to explain why there might be a limit to how much solute will dissolve
in a solvent.
4. Did every group in the class get the same value? If not, why not?
5. Was this investigation a fair test?
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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MAKING CLEAR SOUP
Investigating Solubility
If we examine some ready prepared packets of soup we will get some ideas
about their contents.
Investigation:
What is in a packet of soup?


Each group will examine a packet of dried soup
mix.
Construct a table of the main contents found in
those packets examined. Each group to tabulate
their first six main ingredients from their
assigned packet. Pupils should note that
ingredients are listed in order of greatest quantity to least. The
completed table should reflect this.
A table could look like this:
Table to show the first six main ingredients in Minestrone soup.
ingredients
%
Dried
noodles
18.5
Dehydrated
vegetables
17.5
Potato
starch
N.A.
salt
N.A.
Tomato
powder
N.A.
sugar
N.A.
N.A. = (% content) Not Available

Construct a bar graph of the most common ingredients, found in your
class survey of packet soups.
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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MAKING CLEAR SOUP
Investigating Solubility
Your research may show that the main ones are salt, potato starch and
sugar. Your first investigations will look at the variables involved in the
dissolving of salt, potato starch and sugar.
Can you make any predictions about the dissolving of salt, potato starch or
sugar?
You will notice that the packets of soup you have
examined must be ready in a relatively short time. You
may only have about five minutes from putting it into the
pan to serving the soup. Your ingredients have only this
time to dissolve.
How do the recommended cooking times given on the
packets vary throughout the class?
You will also notice that the instructions on the packet refer to stirring.
Some instructions say to use a whisk or fork rather than a spoon.
Can you think why a whisk or fork is better for stirring dried soup in water
than a spoon?
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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MAKING CLEAR SOUP
Investigating Solubility
Alternative investigation into dissolving:
What do we understand by the word dissolve?
We are going to conduct an investigation to see if the mass of salt affects
how fast the salt dissolves in the water. Using the same volume and
temperature of water, four different masses of salt ( e.g. 10, 20, 30, 40 ml,
use a measuring cylinder for this) will be stirred until no more crystals are
visible. Each mass of salt will be tested three times.
A table for results:
Amount of
salt (ml)
1
Time to dissolve ( min)
Trials
2
3
Average time
to dissolve
(min)
10
20
30
40
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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MAKING CLEAR SOUP
Investigating Solubility
So far we have looked at salt dissolving in water. A clear, colourless
solution results from this.
If we take cornflour and try to dissolve it in water we get a cloudy mixture.
See what happens when you take a dry test tube and add a spatula of
cornflour. Then, add room temperature water half way up the test tube.
Shake the test tube and observe. Write down your observations in the table
below.
Let the test tube rest in a test tube rack for some minutes. You may leave
the test tubes overnight.
Record your observations.
Time ( minutes )
At start, cornflower just added and
shaken
1 minute
Observations
2 minutes
(overnight, optional)
You should have noticed that the test tube of cornflour and water was not
clear. The particles of cornflour were suspended in the water,for a while at
least. The suspension was cloudy. Solutions and suspensions are two
extremes of mixtures. In one the particle is very large. In the other, a
particle is very small. There is something in between and it is called a
colloidal dispersion.
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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MAKING CLEAR SOUP
Investigating Solubility
Solutions, Suspensions and Colloical Dispersions
Investigation: Observing the Properties of Colloidal Dispersions and
Solutions.
Materials:
2  250 ml beakers
powdered gelatine
sodium chloride
light beam source
Method:





Stir 4 g sodium chloride (table salt) into some very hot water in a beaker.
Does it dissolve?
Stir 4 g gelatine into some very hot water in a beaker. Does it seem to
dissolve?
Keep stirring. If some gelatine remains after a lot of stirring, try again
with less gelatine or hotter water.
Examine the beaker. Can you see any difference in it from a beaker of
salt solution?
Shine a narrow beam of light through the beaker. Compare the effect
with the effect of shining the same beam through a salt solution.
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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MAKING CLEAR SOUP
Investigating Solubility
You may have seen an effect like this before. On a clear night, the light
beam from the car’s headlights is barely visible. On a foggy night the beam
is quite visible.
How do you account for this difference?
The particles of gelatine in a colloidal dispersion are called the dispersed
phase. They are like the solute of a solution. The water is called the
dispersing phase. It is like the solvent of the solution. A colloidal dispersion
has certain characteristics. It will scatter a beam of light. It will pass
unchanged through filter paper. Its particles, the dispersed phase, are
visible under a microscope. These characteristics tell us that the particles
of the dispersed phase are small enough to pass through filter paper but
large enough to reflect light. The reflecting of light by colloidal particles is
called the Tyndall effect.
Colloidal particles have unique properties due to their size. They expose
large surface areas and are useful in absorbing poisonous gases, dyes and
other materials.
Why might they be of great importance to our soup design?
Think about flavour and texture. You may have already
explored viscosity in another topic. The dispersal of the
flavouring molecules will be of much importance to the
soup designers.
Colloidal dispersions are not only solids dispersed in
liquids. A solid, liquid or gas may be the dispersed phase
or the dispersing phase. Other examples of colloidal
substances are starch dispersed in water, foam, jellies,
smoke, fog, cell contents of animal tissues, many foods,
drugs and plastics.
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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MAKING CLEAR SOUP
Investigating Solubility
Factors affecting the rate of dissolving
So we have had a look at what is actually in the soup and what sort of state
these substances are. Now we will look at the rate of dissolving.
How can we get the contents to dissolve quickly?
Remember some soups are supposed to be ready in 3 minutes.
What factors will affect the rate of dissolving?
Here are some ideas.
1. The temperature of the water.
2. The amount of the solute. E.g. How much salt or sugar.
3. Stirring and how much stirring.
4. The volume of water used. This will affect the final concentration of
the soup and so the flavour of the soup.
5. The particle size.
For You To Think About:
When we investigate these factors we will have
to devise a fair test. What do we mean by this?
We will only change one variable at a time. How
will we record our results?
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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MAKING CLEAR SOUP
Investigating Solubility
Background information for group work on rate
of dissolving
An examination of the various factors that
affect the rate of dissolving.
You will work in groups to investigate the
various factors you have identified. Choose
one of the workcards. More than one group
could work on the same variable. If you want to
use each others results it will be critical that you
carry out the same investigation procedures. This will allow you to fairly
average the combined results. This is called standardising the technique. It
is also useful if there is an error in, e.g. measuring the masses of salt or the
volume of water to be used.
Why do the soup manufactures have to do this?
If your group has chosen to investigate particle size, how will you determine
the sizes of the particles? A seive might have to be used here.
You should look at the instructions on the various packets of soup.
Do they all follow the same method? If not, can you suggest why not?
Why is the heat reduced after adding the dried soup mix to the boiling
water and stirring it?
When you have finished your investigation into your
chosen factor, a spokesperson from your group will
present the groups results to the class or you will
complete a lab write up of your work or you may
present a powerpoint presentation of your findings.
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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MAKING CLEAR SOUP
Investigating Solubility
Workcard 1:
The Temperature of the Water.
Some of the instructions on the soup packets say to boil water before adding the dried
contents. You will investigate the rate of dissolving of salt in water of different
temperatures.
Materials:
4  100 ml
beakers
measuring cylinder
thermometer
hot plate/ kettle
sodium chloride
spatula
stirring rod
labels/waterproof pen
stopwatch
Method:
Label the four beakers 1,2,3, and 4. Add equal volumes of water at these temperatures. 10
o
C, 20 oC, 40oC, 60oC. Add equal masses of sodium chloride to each of the four beakers. If
you decide to stir, all beakers must be stirred the same way.
Results:
Record you results in a table:
Beaker
Temperature oC
At start
At end
Time (secs) to dissolve
1
2
3
4
Evaluation of Results:
How do you know the temperature was measured correctly?
What would be the advantage of repeating your investigation and taking an average of your
results?
Why measure the temperature at the start and at the end of the investigation?
Conclusion:
What does your investigation tell you about the effect of the temperature of the water on
the rate of dissolving? What advice would you suggest when heating water for dissolving
dried soup mix?
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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MAKING CLEAR SOUP
Investigating Solubility
Workcard 2
The amount of the solute. E.g. How much salt or sugar will dissolve in a given amount
of water?.
Look at the soup packets. How much do they contain? You could work out how much sugar
there is in your packet of soup by examining the nutritional data. The data will be given for
100g. Your packet may contain less than this. You will investigate how much salt or sugar
will dissolve in a given amount of water.
Materials:
4  100 ml beakers
thermometer
measuring cylinder
hot plate/ kettle,
(optional)
sugar/salt
spatula/balance
stirring rod
labels/waterproof pen
stopwatch
Method:
Label the four beakers 1,2,3, and 4. Add equal volumes of water, all at the same
temperature. Add your selected numbers of spatulas of salt or sugar to each of the four
beakers. If you use a balance to weigh different masses of solute record that in the table
below. If you decide to stir, all beakers must be stirred the same way. Time how long they
take to dissolve.
Results:
Record your results in a table:
Beaker
Numbers of spatulas of
salt/sugar or masses of solute
Time (secs) to dissolve
1
2
3
4
Evaluation of Results:
How do you know the spatulas were all the same measurement?
What would be the advantage of repeating your investigation and taking an average of your
results? Do you think there will be a difference between salt or sugar?
Conclusion:
What does your investigation tell you about the effect of changing the masses of solute on
the time taken to dissolve? What restrictions do you think the soup manufacturers have as
to the mass of dried soup mix that can go in a packet?
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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MAKING CLEAR SOUP
Investigating Solubility
Workcard 3
Stirring and How Much Stirring?
What will you stir with? What is suggested on the packet? How will you standardize your
stirring technique? A magnetic stirrer may be of use to you here.
Materials:
4  100 ml beakers
measuring cylinder
thermometer
hot plate/ kettle,
(optional)
sugar/salt
spatula/balance
stirring rod
labels/waterproof pen
stopwatch
Method:
Label the four beakers 1,2,3, and 4. Add equal volumes of water, all at the same
temperature. Add the same mass of salt or sugar to each of the four beakers. Decide what
you will use to stir your solution with. This could be a stirring rod, a spoon, a spatula, a fork
or a magnetic stirrer. All beakers must be stirred the same way but for different lengths
of time or at different rates. Time how long they take to dissolve.
Results:
Record your results in a table:
Beaker
Stirring times or rates
Time (secs) to dissolve
1
2
3
4
Evaluation of Results:
How could you ensure that the stirring rates were all changed in one aspect only? What
would be the benefits of a magnetic stirrer?
Conclusion:
What advice would you now give on the soup packet for stirring utensil? Do you think it
would be important as to when the soup was stirred? Are there any differences on this in
the instructions on your soup packets?
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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MAKING CLEAR SOUP
Investigating Solubility
Workcard 4
The Volume of Water Used.
Why will it be important to use water at the same temperature? Is there a minimum volume
of water that could be used? How could this be determined?
Materials:
4  100 ml beakers
measuring cylinder
thermometer
stirring rod
labels/waterproof pen
stopwatch
hot plate/ kettle,
(optional)
sugar/salt
spatula/balance
Method:
Label the four beakers 1,2,3, and 4. Add your selected volumes of water,
all at the same temperature. Add the same mass of salt or sugar to each
of the four beakers. All beakers must be stirred the same way, at the
same rate.Time how long they take to dissolve.
Results:
Record you results in a table:
Beaker
Volume of water (ml)
Time (secs) to dissolve
1
2
3
4
Evaluation of Results:
Did you choose an even range of volumes of water? Why might this be of importance?
Conclusion:
How much water do soup manufacturers allow for dissolving their soup mix? What factors
do you think they have had to consider? How many people are the packets, on average,
supposed to feed?
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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Investigating Solubility
Workcard 5
The Particle Size. It would be possible to look at granulated, castor and icing sugar here.
You will have more particle size choices if you choose brown sugar.
Materials:
4  100 ml beakers
measuring cylinder
thermometer
hot plate/ kettle, (optional)
sugar ( granulated, castor, icing) /salt
(sea salt, powdered salt) You need four
choices here.
spatula/balance
stirring rod
labels/waterproof pen
stopwatch
Method:
Label the four beakers 1,2,3, and 4. Add the same volumes of water, all at the same
temperature. Add the same mass of salt or sugar ,of the chosen particle size, to each of
the four beakers. All beakers must be stirred the same way, at the same rate.Time how long
they take to dissolve.
Results:
Record you results in a table:
Beaker
Particle size
Time (secs) to dissolve
1
2
3
4
Evaluation of Results: How did you decide the range of particle sizes? Why might this be
of importance? How could you measure particle size more scientifically? Your work on soil
particle size might help you here. What units can be used for particle size?
Conclusion: Do any soup manufacturers use brown sugar in their ingredients? Why might
they use brown instead of white sugar? What other factors about particle size do you think
they have had to consider? Might there be any disadvantages to using icing sugar?
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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Investigating Solubility
Workcard 6
Can you think of another factor the soup manufacturers might have to consider? How could
you investigate this? Make up your own work card, using the methods used before, to
investigate your chosen variable.
Variable:
Materials:
Method:
Results:
Evaluation of results:
Conclusion:
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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Investigating Solubility
Teacher Supplementary Notes
Teacher Demonstration
You have got two beakers of water, one has salt and the other
does not. You heat them both for the same length of time.
Do they both end up at the same temperature?
Make a prediction about your experiment.
Teacher Discussion of the hypothesis that:
The time required to cause a change in
temperature increases as the amount of material
dissolved in the water increases. The more
dissolved substance the less the rise in
temperature.
Investigation of the hypothesis
Your first experiment will look at collecting data to test this hypothesis/
prediction. The equipment list and directions you need are given below:
4  100 ml pyrex beakers
1 graduated measuring cylinder
1 spatula
1 hot plate/ bunsen burner + tripod
+ heat mat
1 thermometer
1 stopwatch
sugar or salt
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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Investigating Solubility
Method:






Label the beakers 0,1,2 and 3.
Measure 50 ml of water into each.
Dissolve one spatula of salt or sugar in beaker 1 and 2 spatulas in
beaker 2; and 3 in beaker 3.
Do not put any sugar or salt in beaker 0.
Heat each beaker for three minutes.
Record the change in temperature in the table below.
Amount of sugar or salt
(spatulas)
0
1
2
3
Temperature change
( oC)
Why did you use beaker 0?
What do your results show?
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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Investigating Solubility
Examining the concept of controls in experiments.
To know that the sugar or salt is causing the change, you
need to know what happens when no sugar or salt is used.
The beaker with no sugar or salt is a standard of
comparison to which all the other beakers can be
compared. Most experiments include a standard of
comparison, called a control or control group.
In some experiments, such as this one, the control is called the no
treatment control. In other experiments all groups receive a treatment
(some amount of the manipulated variable).
The experimenter must then select one of the levels of the manipulated
variable to serve as the control group. The
level selected is usually the normal or typical
case.
For example, in an experiment on the effect of
depth of seed on seed germination, the control
might be the recommended or normal planting
depth; other planting depths might be deeper
or shallower than the control. This kind of control is called an
experimenter-selected control.
Using the data collected from your experiment, construct
a graph and a statement about the relationship between
the amount of dissolved sugar or salt and the rate of
temperature change. Be sure to give the graph a title.
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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Investigating Solubility
Statement of Relationship
The temperature change decreases, as the amount of
dissolved sugar or salt increases. The addition of e.g.
more than two spatulas of sugar or salt results in no
increase in temperature change. The more dissolved
substance, the more heat required to get to a given
temperature. Your statement may be different depending on your
experimental results.
Questions:
1. What does this tell a soup manufacturer?
2. What advice could you now give to the soup manufacturer?
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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Investigating Solubility
Further related investigations and identifying variables.
Now we are going to use these findings and investigate soup solubility
further.
1. What is the effect of temperature on the time a
stock cube takes to dissolve?
2. Does the mass of the stock cube have an effect on
the temperature change of the water?
3. Does the temperature of the water effect the change in temperature
when adding the stock cube?
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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Investigating Solubility
Investigation:
Examine the question in more detail.
What are some of the variables that could affect the
dissolving time of the stock cube?
1.
2.
3.
4.
5.
6.
Amount of water
Mass of stock cube
Type of stock cube
Shape of container
Temperature of the water
Length of stirring time
If the variable, temperature of the water, was selected for your
investigation, you could make this prediction: The time required to totally
dissolve a given mass of stock cube decreases with an increase in the
temperature of the water acting as the solvent. You will now gather data to
test your hypothesis. The equipment list and directions on what to do are
given below.
Method
4  100 ml pyrex beakers
4  500 ml pyrex beakers
1 graduated measuring cylinder
1 knife
1 balance
1 hot plate
1 thermometer/ 4 stick-on
thermometers
stock cubes
stop watch
waterbaths at 10oC, 20oC, 40oC,
and 60oC
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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Investigating Solubility
Method (continued):
 Label your 100 ml beakers 1,2,3, and 4.
 Measure 50 ml of water into each as follows;
Beaker
1
2
3
4
Temperature of
water oC
10
20
40
60

Place the 100 ml beaker into a 500 ml beaker of water at the required
temperature. This will help to maintain the correct temperature.

Using your knife and the balance, measure four equal pieces of stock
cube.
Note the temperature of each beaker and add the pieces of stock
cube simultaneously to each.
Time how long it takes for the stock cube to dissolve. Once the
experiment is finished note the temperature in all beakers.


Beaker
Temperature
o
C
Time
(min)
Observations on stock cube
1
2
3
4

Draw a pie chart to show the differences in each stock cube, using
different colours for each temperature.
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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Investigating Solubility
Skills needed when identifying variables
After completing this assignment you should be able to:
1. Identify the variables in a written statement or
description of an investigation.
2. Classify the variables as independent or dependent.
You will have to make several measurements in the following activities. This
will help you to identify the different variables involved.
Investigation
To identify different variables involved in the solubility of calcium chloride.
Method:
Safety goggles
4 small identical beakers
thermometer
spatula
stirring rod
1 litre beaker
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calcium chloride ( this is a
chemical used to control ice
on roads)
graduated cylinder
labels/pen
Fill the litre beaker with tap water at room temperature.
Use the graduated cylinder to fill each small beaker with
75 ml of water.
Measure the temperature of the water in one of the
beakers.
Label it container A.
Add one spatula of calcium chloride and using a stirring rod,
stir until it dissolves.
Measure the temperature of the water as soon as the calcium chloride
has dissolved.
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
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MAKING CLEAR SOUP
Investigating Solubility
Answer the following questions:
1. What was the initial temperature of the water before
adding the calcium chloride?
2. What was the temperature after adding the calcium chloride?
3. What happened to the temperature of the water in the beaker?
4. How many degrees did the temperature change when you added one
spatula of calcium chloride?
You may have found that the temperature increased about 3 to 6 degrees
Celcius. The temperature could be more or less than this depending on the
amount of water you used and the amount of calcium chloride.
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You will now record your measurements in the table below.
You should record both the number of spatulas of calcium chloride
added and the change in temperature for each small beaker.
Beaker
Number of spatulas of
calcium chloride
Temperature change
(oC)
A
B
C
D
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
Page 29
MAKING CLEAR SOUP
Investigating Solubility
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Repeat the procedure described for beaker A with beaker B. This
time add two spatulas of calcium chloride.
Again, determine how much the temperature changes from the initial
temperature of the water.
Record your data in the table.
Repeat the procedure for beakers C and D, using three and four
spatulas of calcium chloride respectively.
Answer the following questions:
1. Did you use the same amount of water in each beaker?
2. Did you use the same amount of calcium chloride in each beaker?
3. Did the temperature change the same amount for each beaker?
4. What prediction would you make if you added five spatulas of calcium
chloride to the same amount of water?
If you followed the directions carefully, you should have used the same
amount of water in all four beakers. You should have added different
amounts of calcium chloride to each beaker ( one spatula to beaker A, two to
beaker B, three to beaker C and four to beaker D,) The temperature should
have increased by different amounts in the beakers.
The increase was greater for those beakers in which
more calcium chloride was dissolved. Finally, you
probably predicted that the temperature change would
be even greater if five spatulas of calcium chloride were
added.
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
Page 30
MAKING CLEAR SOUP
Investigating Solubility
Technical Guide:
Graduated cylinders
Beakers
Water
Salt (25g on a piece of paper)
Stirring rods
Spatulas
Balances
Selection of packet soups to
compile list of ingredients
Graph paper
Thermometers
Graduated cylinders
Salt
Stirring rods
Spatulas
Cornflour
Test tubes
Test tube racks
Torch/light source to show colloids
Gelatine
Beakers
Sodium chloride (salt)
Materials for Workcards 1-5
100 ml beakers ( need four per
group)
measuring cylinders
thermometers
hot plate/kettle
sodium chloride ( table salt, sea
salt, powdered salt) or sugar ( icing
sugar, caster sugar, granulated
sugar)
spatulas
stirring rods / magnetic stirrers
labels/ waterproof pens
stopwatches
balances
spoons, forks, knives
Stock cubes
Measuring cylinder
Knife
Balance
Hot plate
Thermometer
Stopwatch
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
Page 31
MAKING CLEAR SOUP
Investigating Solubility
Materials needed to do workcards 1 – 5
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100 ml beakers ( need four per group)
measuring cylinders
thermometers
hot plate/kettle
sodium chloride ( table salt, sea salt, powdered salt)
or sugar ( icing sugar, caster sugar, granulated
sugar)
spatulas
stirring rods / magnetic stirrers
labels/ waterproof pens
stopwatches
balances
spoons, forks, knives
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
Page 32
MAKING CLEAR SOUP
Investigating Solubility
Glossary
o Colloidal dispersion: a dispersion where the dispersed particles are
larger than molecules but smaller than the particles in true suspension
o Concentration: strength of a solution
o Diffusion: movement of molecules from an area of high concentration
to an area of low concentration
o Dissolve: to mix completely a solute with a solvent to form a solution
o Emulsion: a mixture in which one liquid is dispersed in another, such as
oil in water
o Heterogeneous: not of uniform composition
o Homogenous mixture:of uniform composition throughout
o Insoluble: unable to be dissolved
o Mechanical mixture: a mixture made up of two or more easily
identifiable parts
o Molecular: composed of molecules
o Molecules: the smallest part of a pure substance which retains the
properties of that substance. It may consist of one or more atoms.
o Phase: a uniform part of a mixture
o Saturated: not able to dissolve any more solute
o Solubility: the property of being able to dissolve. More specifically, it
refers to the mass of a solute that can dissolve in a given amount of
solvent to form a saturated solution at a particular temperature
o Soluble: able to be dissolved
o Solute: the substance that dissolves in a solvent to form a solution
o Solution: the product formed when a solute dissolves in a solvent
o Solvent: the substance that dissolves a substance to form a solution
o Supersaturated: a solution that contains more dissolved solute than
can normally be dissolved in a given mass of solvent at a particular
temperature
o Suspension: a mixture containing floating particles that will settle
after sometime
o Tyndall effect: the scattering of a beam of light by reflection from
tiny suspended particles
o Unsaturated: able to dissolve more solute
5-14 Environmental Studies, Science, Levels E and F
National Curriculum, Key Stage 3
Page 33