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Chemistry Term 1
Unit 1 – Particles
C1.2
Any short list of elements will do. Some examples
students might offer include: hydrogen, oxygen,
carbon, iron, tin, lead, gold, silver, silicon.
C1.4
Any solid materials will do. Some examples
students might offer include: wood, metal, glass,
paper, plastics.
C1.6 TB
The important aspect of this answer is that the
students can demonstrate their understanding of
the particle model of solids, liquids and gases by
communicating with others. It is worth asking them
to repeat their explanations in class.
Unit 2 – Particle behaviour
C2.1
Any substances that can be observed to have
changed when heated or cooled will do. Some
examples include: ice melting to liquid, and
freezing back again; heated metals that give off
heat or light and expand in size; plastics that melt
when heated then solidify again in different
shapes; glass that is heated until it is liquid then
shaped and cooled into objects.
C2.4
The purple potassium permanganate particles are
pushed around by the particles of water in random
directions. Slowly, this separates the purple
particles and they begin to mix in among the water
particles. The purple colour steadily spreads out
through the water in the beaker.
C2.5 (1)
At this temperature, the water in a pond will freeze
completely. The ice will form first on the surface,
then the ice will form deeper and deeper until the
whole pond is frozen.
C2.7
A thermometer contains a coloured liquid. As the
temperature rises, the liquid expands and fills
more of the tube of the thermometer, so the level
of the liquid rises up the tube. If the temperature
goes down, the liquid contracts and the level falls.
C2.7 TB
As the temperature rises, the air in the beaker
expands and pushes the water out of the bottom,
open end of the beaker. Eventually the air expands
to fill the beaker, and if the temperature rises high
enough bubbles of air will escape from inside
the beaker.
The particles of air move faster and faster as the
temperature rises. They collide with the particles of
water and push harder and more often. This
causes higher pressure on the water, pushing it
out of the open end of the beaker.
Unit 3 – Mixtures and solutions
C3.1
Any mixtures will do. Some examples that student
may suggest include:
 Milky tea is a mixture containing tea dissolved
in water and particles of milk. If you like sweet
tea, then sugar will also be dissolved in the
water.
 Sand from a beach is a mixture of particles of
silicon dioxide with tiny pieces of minerals and
other substances.
 We often dissolve salt (sodium chloride) in
water when we are cooking foods. This gives
food a different flavour, but also the salt helps
make the water boil at a higher temperature
than 100 °C, cooking the food faster.
 If you look at the label of a bottle of bath foam,
you will see it contains several different
substances. These mix with the water in the
bath and colour it, and cause it to produce
bubbles. Also, many bath foams contain
substances to give the bath a pleasant smell.
C2.5 (2)
Anything that is denser than water will sink;
anything that is less dense than water will float.
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Chemistry Term 1 – Answers to Student’s Book questions
Answers: Student’s Book questions
Chemistry Term 1 – Answers to Student’s Book questions
Answers: Student’s Book questions
C3.2
C5.4
There are many everyday soluble mixtures. Some
examples include:
1. Hot water vapour is cooling down.
2. The water vapour is condensing to form liquid.
The temperature does not change until all the
water has condensed.
3. The liquid is cooling down.
 salt in water
 sugar in water or hot drinks
 baking powder (sodium hydrogen carbonate).
The liquid is freezing to become ice. The
temperature does not change until all the water
has become ice.
C3.3 TB
The chemicals in nail varnish will not dissolve in
water, so it makes no difference if it is cold or
hot water.
4. The ice is cooling down.
C5.4 TB
C3.4
Solid water: hail, snow
We can tell if a solution is saturated because when
more solute is added, it will not dissolve. We can
investigate this by part filling a beaker with cold
water and measuring its temperature with a
thermometer, then carefully adding measured
amounts of salt until no more will dissolve. We
record that mass of salt, then heat the water to
a higher temperature, and measure how much
more salt we can dissolve until the solution is
saturated again. We can repeat this at different
temperatures.
Liquid water: rain and clouds
Gaseous water: water vapour in the air
Flow chart:
[liquid water in the sea]

[water vapour in the air]

[liquid water droplets form clouds]

[liquid water falls as rain, or frozen
water falls as snow or hail]
C3.10 (1)
Blue and yellow paint
C5.5
C3.10 (2)
First, distil the water by heating the mixture in a
distilling flask connected to a condenser. The
steam formed will condense in the condenser tube,
and the liquid collected will be pure water.
The energy goes into the surroundings, for
example a hot liquid cooling in a beaker gives out
energy to warm the beaker and the air above it.
Once nearly all the liquid in the distilling flask has
been boiled, it can be left to evaporate and salt
crystals will form as it cools.
Unit 5 – Changing materials
C5.3
People breathe out water vapour in the air that
comes out of their lungs, and there is water vapour
naturally present in the air around us, even when
the weather is dry. People warm the air up inside
a tent, and the outside of the tent can get cold at
night, so the water vapour in the air inside the
tent condenses on the inside surface of the tent
because the surface gets colder than the air inside
the tent.
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TEACHER’S HANDBOOK 1
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Chemistry Term 1 – Answers to Student’s Book questions
Answers: Student’s Book questions
C5.6
Substance
water
Melting point
(°C)
0
100
−114
ethanol
(alcohol)
Boiling point
(°C)
78
carbon
dioxide
−78
−55
oxygen
−219
−183
nitrogen
−210
−196
mercury
−39
357
iron
1538
2861
lead
327
1749
C5.7
100 g; because the mass of water stays the same.
C5.8
As the water starts to freeze in a pond, the ice
floats on the surface. The top of the water freezes
first. The liquid water at the bottom of a pond is the
last to freeze.
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