National 5
Unit 3
1.
2.
3.
4.
Metals
Plastics
Fertilisers
Nuclear Chemistry
Homework Booklet
1
Exercise 1 – Metals Revision
1. Aluminium is used to make aircraft, ladders and cooking foil. Copper is used to make
hot and cold water pipes, wiring and the bases of cooking pots. Copy the following
table and use this information and your knowledge of properties of metals to complete
it.
Metal
Use
3 Properties which make the metal suitable for
these uses
2. The results of experiments with the metals A, B, C and D are shown below:
Metal
A
B
C
D
Reaction with cold water
No reaction
Hydrogen formed
Very slow reaction
No reaction
Reaction with dilute acid
Hydrogen formed
Hydrogen formed
Hydrogen formed
No reaction
a) Use this information to place the metals in order of reactivity, starting with the
most reactive.
b) Suggest a name for each of the metals A, B, C & D.
3. A pupil carried out an experiment on potassium oxide, tin oxide and mercury oxide. On
heating the three metal oxides it was found that one decomposed to form a liquid
metal and oxygen gas. On heating with carbon, one of the other metal oxides reacted
to form the metal.
a) Which metal would decompose on heating alone?
b) Which metal would decompose on heating with carbon?
c) Suggest a method of extracting the final metal from its oxide.
4. Metals are often mixed with other metals to improve the chemical and physical
properties of the metal.
a) What is the name given to these mixtures?
b) Name 2 of the mixtures, give the metals present in the mixture and 2 uses for
each.
2
Exercise 2 – Metals
1. a) Which of the following substances will conduct electricity?
Gold foil, hydrogen gas, sulphur powder, magnesium ribbon, bromine liquid
Phosphorous sticks, liquid oxygen, copper foil.
b) What do the substances that conduct have in common?
c) Using your knowledge of chemistry, explain what is meant by a metallic bond and
how a metal is able to conduct electricity. You may wish to use a diagram.
2. Copy and complete the following word equations for the reaction of metals.
a) Zinc + hydrochloric acid
b) Potassium + water
c) Iron(III) + oxygen
3. Using your answers for Q1, write out the ionic equations for each of the reactions.
4. Pure gold is known as 24-carat gold. In jewellery, is often mixed with other metals to
make it harder. One common mixture is 9-carat gold. It’s composition by mass is shown
in the pie chart.
a) What name is given to a mixture of metals such as 9-carat gold?
b) A 9-carat gold ring weighs 7.88g. Calculate the mass of gold in the ring.
3
Exercise 3 – Electrochemical Cells
1. The voltages between pairs of metals can be used to place them in the electrochemical
series.
Metal
Voltage
Direction of
(V)
electron flow
1
0.6
Metal to copper
2
0.2
Copper to metal
3
0.9
Metal to copper
4
0.1
Copper to metal
a) Give the order of reactivity of the metals 1 – 4, starting with the most reactive.
b) Suggest a name for each of the metals.
2. a) Copy and complete the following word equations and decide which will react.
1.
2.
3.
4.
5.
6.
Zinc(II) + copper(II) sulphate
Zinc(II) + iron(II) nitrate
Iron(II) + magnesium chloride
Iron(II) + lead(IV) chloride
Copper(II) + silver(I) sulphate
Copper(I) + lead(IV) nitrate
b) Using your answers from a), where a reaction occurs, write ion electron half equations
for each of the reactions.
c) Label each of these equations either oxidation or reduction.
d) Then combine these half equations to write a balanced redox equation.
4
Exercise 4 – Plastics Revision
1. There are different types of plastics; thermosetting and thermoplastic.
a) Explain the 2 terms underlined.
b) Give an example of a plastic for each of these terms along with a use.
2. Copy and complete the following table:
Monomer
Ethene
Polymer
Polyvinyl chloride
Terafluoroethene
Polystyrene
3. Using your knowledge of chemistry, discuss the advantages and disadvantages of
plastics, including their uses, effect on society and the environment.
4. Smart materials are new developments in material science, they have many useful
properties. Give 2 examples of smart materials, explain their use and why they are
used for this purpose.
5
Exercise 5 – Polymers
The following 4 questions refer to the burning or smouldering of some plastics.
Decide which of the following toxic gases could be produced when the plastic is burnt,
there could be more than one answer.
A: Carbon monoxide
B: Hydrogen chloride
C: Hydrogen cyanide
1.
2.
3.
4.
5. A polymer can be represented as follows:
a) How many repeating units are shown?
b) Draw the structure of the monomer unit.
c) What type of polymerisation occurs in the formation of this polymer?
6. Poly(propene) is used to make many kitchen items.
a) Name the monomer unit.
b) Draw the full structural formula for the monomer unit.
c) Draw the structure of a part of the poly(propene) chain to show 3 monomer units
joined together.
7. PTFE is an addition polymer made from tetrafluoroethene.
a) What dies PTFE stand for?
b) Draw the full structural formula for tetrafluoroethene.
c) Draw the structure of a part of the PTFE chain to show 3 monomer units joined
together.
6
Exercise 6 - Polymers
1. Nylon is a polymer with many uses.
It is a synthetic thermoplastic
polymer.
a) What is a thermoplastic polymer?
b) What is a synthetic polymer?
c) Give 2 other examples of synthetic polymers.
Nylon is a polymer made from two different monomers as shown.
d) Suggest a name for this type of polymerisation.
2. Two different forms of nylon are nylon 6 and nylon 6,6.
a)
b)
c)
d)
e)
Draw the structure of the repeating unit of nylon 6.
Draw the structure of the monomer from which nylon 6 is made.
Draw the structure of the repeating unit of nylon 6,6.
Draw the structure of the two monomer units from which nylon 6,6 is made.
What type of polymerisation occurs in the formation of nylon6 and nylon 6,6.
3. a) Which one of the following substances can be used to prepare an addition polymer?
b) Which two can be used to prepare a condensation polymer?
c) Using your answer to part a) draw 3 monomer units joined together to make a
polymer chain.
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Exercise 7 – Fertilisers Revision
1. Fertilisers are compounds which restore to the soil essential elements for plant
growth.
a) Name three elements which are restored to the soil through the use of fertilisers.
b) Explain how synthetic fertilisers are produced, mention the chemical reaction
involved.
c) Natural fertilisers can be used by farmers as an alternative to synthetic
fertilisers. Suggest another way farmers can improve the soil without using
synthetic fertilisers.
2. Calculate the % mass composition of nitrogen in the following compounds:
a) KNO3
b) (NH4)3(PO4)
c) Calcium nitrate
d) Ammonium nitrate
3. Potassium nitrate fertiliser can be produced by reacting potassium hydroxide with
nitric acid. Water is also formed.
a) Write this reaction as a word equation.
b) Write out a balanced ionic equation for this reaction.
c) Identify the spectator ions.
d) Name the type of chemical reaction that is taking place.
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Exercise 8 – Ammonia
Decide whether each of the following statements are:
A: True
or
B: False
1. Ammonia is made in industry from nitrogen and water.
2. The reaction is likely to be carried out at a very low temperature.
3. The catalyst increases the rate of the reaction.
4. The reaction is called the Haber Process.
5. An iron catalyst is used in the reaction.
6. Ammonia gas is cooled to remove it from the unchanged reactants.
7. The nitrogen for the reaction is obtained from nitrogen oxides.
8. The gases in the reaction chamber are kept at low pressure.
9. The catalyst is used to prevent the ammonia decomposing.
10. One of the reactants is obtained from methane (natural gas).
11. All the reactants are converted to ammonia.
12. Ammonia is produced from nitrogen and hydrogen.
13. The catalyst is used up in the reaction.
14. The word equation for the reaction is:
Nitrogen oxide + hydrogen
ammonia + oxygen
15. The unchanged reactants can be recycled.
16. The catalyst provides the surface on which the reaction takes place.
17. Ammonia is used to make fertilisers.
18. The catalyst speeds up the formation of ammonia.
19. The nitrogen for the reaction is obtained by fractional distillation of liquid air.
20. The reaction is likely to be carried out at a very high temperature.
21. Using your knowledge of chemistry, describe the properties and uses of ammonia, this
could include the industrial production of ammonia.
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Exercise 9
1. Ammonia is produced in the Haber process.
The percentage yield of ammonia, obtained at different pressures, is shown in the
table.
Pressure (atms)
% yield of ammonia
50
6
100
10
150
14
200
19
250
22
350
29
400
32
a) Draw a line graph of the results.
b) Using your graph, estimate the yield of ammonia at 300 atmospheres.
Temperature is another factor which affects the percentage yield of ammonia.
c) Suggest a reason why 500oC is the temperature chosen to operate an industrial
ammonia plant rather than 200oC.
2. Ammonium phosphate, (NH4)3(PO4), is a synthetic fertiliser that is prepared by the
reaction of ammonia with phosphoric acid, H3PO4.
a) Write a balanced chemical equation for this reaction.
b) Calculate the mass (g) of 5 moles of ammonium phosphate.
3. A student carried out two experiments on compound X.
A colourless gas was
given off and the
limewater became
cloudy.
a)
b)
c)
d)
A gas was given off
which turned the pH
paper blue.
Name the gas given off by experiment 1.
Name the gas given off by experiment 2.
Name compound X.
Write an ionic equation to show the reaction of X with sulphuric acid.
10
Exercise 10 – Atomic Structure Revision
1. Using your periodic table, copy and complete the following table:
Atom /
Ion
Atomic
No
3
Mass
No
No of
electrons
No of
protons
No of
neutrons
4
Nuclide
Notation
14
12
6
Aluminium
14
12
12
19
7N
40
2. What is an isotope?
3. Explain whether the following pairs of atoms are isotopes:
a) 35Cl and 37Cl
b) 14C and 14N
4. In an experiment using a mass spectrometer, it was found that a sample of neon from
the air had 3 isotopes.
Isotope
Abundance %
20
Ne
90.5
21
Ne
0.3
22
Ne
9.2
Calculate the relative atomic mass of neon given this information.
11
Exercise 11
1. We are all exposed to small amounts of radiation in our everyday lives, this is referred
to as background radiation. Give 2 sources of background radiation.
2. Copy and complete the following paragraph using the words in the box.
Helium
electromagnetic
penetrating hydrogen
electrons
isotopes
protons
unstable
chemical
nucleus
_____________ of some elements are radioactive. This is because they have an
_____________ nucleus.
There are three main types of radioactive decay. Alpha particles are _________
nuclei, beta particles are fast moving ____________ and gamma radiation is made up
of very ___________ _____________ radiation.
All three types of radiation come from the __________ of atoms.
3. Write equations to show how the following isotopes decay when they emit alpha
particles.
a)
b)
4. Write equations to show how the following isotopes decay when they emit beta
particles.
a)
b)
5. In each of the following questions, give the full nuclide notation of the atom formed
after the sequence of emissions stated.
a)
b)
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Exercise 12
1. Carbon-14 is a radioisotope. Copy and complete the nuclear equation to show it’s
decay:
a) Some carbon-14 is present naturally in the atmosphere. What name is given to
radiation from a source like this?
b) Carbon-14 is used in radiocarbon dating to find the age of archaeological
remains such as wood. Suggest 2 reasons why carbon-14 is suitable for this
purpose.
2. Albert has been given 16g of a radioactive isotope for his 12th birthday. The
isotope has a half-life of 8 years.
a) What is meant by the term half-life?
b) What mass of the isotope will Albert have when he is 20?
c) How old will Albert be when he has 2g of the isotope left?
3. A radioisotope has a half-life of 1 hour. What percentage of the isotope will remain
after 3 hours?
4. After 180 seconds the count rate from a radioisotope dropped from 512 counts per
minute to 8 counts per minute. Calculate the half-life of the radioisotope.
5. The radioactivity of a different radioisotope was measured over a period of time.
a) Use the data below to draw a graph of time versus counts per second.
Time (s)
Counts per sec
0
90
5
75
10
61
15
50
25
36
30
29
42
21
60
10
b) From the graph, calculate the half-life of the radio isotope.
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