GCSE Physics Revision: 3) Particle Model V1

Q1.

Density can be explained using the particle model.

(a)What is the unit of density (ρ)?

Tick one box.

joules, J /
joules per kilogram, J / kg /
kilograms, kg /
kilograms per metre cubed, kg / m3 /

(1)

(b)The figure below shows particles of the same substance in three states of matter.

Use the figure above to explain why the solid has the highest density.

______

(2)

(c)Complete the sentences.

Use answers from the box.

downwards / kinetic / nuclear / potential / randomly / slowly

The particles in a gas are constantly moving.

The particles move ______

When the temperature of the particles in a gas is increased

the particles have more ______energy .

(2)

(d)A gas is put into a closed container.

The container and the gas inside it are heated.

What will happen to the pressure inside the container?

______

(1)

(Total 6 marks)

Q2.

The bar chart shows the amount of energy needed to raise the temperature of 1 kg of three materials by 20 °C. The materials are used inside heaters.

(a)Which material stores most energy?

______

(1)

(b)The heaters that use the different materials are shown below. The power output when the heaters are being used is shown below each picture.

Each heater is put in one of three identical rooms. Each room’s temperature is 10 °C and the heaters are switched on for 5 hours.

Which heater would cause the biggest temperature rise in the room?

Give a reason for your answer.

Heater ______

Reason ______

(2)

(c)Aluminium has a specific heat capacity of 900 J/kg °C.

Calculate how much energy is needed to raise the temperature of 2 kg of aluminium
by 15°C.

Use the correct equation from the Physics Equations Sheet.

Show clearly how you work out your answer.

______

Energy = ______J

(2)

(Total 5 marks)

Q3.

(a)The diagrams show the arrangement of the particles in a solid and in a gas.

Each circle represents one particle.

(i) Complete the diagram below to show the arrangement of the particles in a liquid.

(2)

(ii)Explain, in terms of the particles, why gases are easy to compress.

______

(2)

(b) The diagram below shows the model that a science teacher used to show her students that there is a link between the temperature of a gas and the speed of the gas particles.

The ball-bearings represent the gas particles. Switching the motor on makes the ball-bearings move around in all directions.

(i) How is the motion of the ball-bearings similar to the motion of the gas particles?

______

(1)

(ii)The faster the motor runs, the faster the ball-bearings move. Increasing the speed of the motor is like increasing the temperature of a gas.

Use the model to predict what happens to the speed of the gas particles when the temperature of a gas is increased.

______

(1)

(Total 6 marks)

Q4.

Solid, liquid and gas are three different states of matter.

(a)Describe the difference between the solid and gas states, in terms of the arrangement and movement of their particles.

______

(4)

(b)What is meant by ‘specific latent heat of vaporisation’?

______

(2)

(c)While a kettle boils, 0.018 kg of water changes to steam.

Calculate the amount of energy required for this change.

Specific latent heat of vaporisation of water = 2.3 × 106 J / kg.

______

Energy required = ______J

(2)

(d)The graph shows how temperature varies with time for a substance as it is heated.

The graph is not drawn to scale.

Explain what is happening to the substance in sections AB and BC of the graph.

Section AB ______

______

Section BC ______

______

(4)

(Total 12 marks)

Q5.

The figure below shows a simple model of the three states of matter.

(a)What is the correct equation to work out the density of a material?

______

(1)

(b)A student explains density to his teacher using the particle model in the figure above.

His teacher says there are limitations to the model.

Give two limitations of the particle model in the figure above.

1. ______

______

2. ______

______

(2)

(c)When the gas in a container with a fixed volume is heated, the pressure increases as the temperature increases.

Explain why the pressure increases.

Use the model in the figure above to help you.

______

(4)

(Total 7 marks)

Q6.

The picture shows a person taking a hot shower.

(a) When a person uses the shower the mirror gets misty.

Why?

______

(3)

(b) The homeowner installs an electrically heated mirror into the shower room.

When a person has a shower, the heated mirror does not become misty but stays clear.

Why does the mirror stay clear?

______

(2)

(Total 5 marks)

GCSE Physics Revision: 3) Particle Model V1

Mark schemes

Q1.

(a) kilograms per metre cubed, kg / m3

(b) (solid has) more particles

allow atoms for particles

in the same volume orin a given volume

allow description of a given area

this order only

kinetic

(d) (pressure) rises

[6]

Q2.

(a)water

allow H2O / OH2

(b)water (filled heater)

allow 3kW

highest power (output) / most powerful / highest number of watts

only scores if first marking point correct

allow highest energy / heat output

allow has more power

ignore stores most energy /references to heat

(c)E = m × c × θ

27 000

allow 1 mark for correct substitution into correct equation:

2 × 900 × 15

2000 × 900 × 15

27 000 000

[5]

Q3.

(a) (i)random distribution of circles in the box with at least 50 % of circles touching

random distribution of circles occupies more than 50 % of the space

judged by eye

(ii)(large) gaps between particles

accept particles do not touch

accept particles are spread out

(so) easy to push particles closer (together)
or
forces between particles are negligible / none

an answer in terms of number of particles is insufficient

(b)(i)(both are) random

accept a correct description of random eg unpredictable or move around freely or in all directions

they take up all the space is insufficient

they are spread out is insufficient

they move in straight lines is insufficient

(ii)(speed also) increases

[6]

Q4.

(a)solid
particles vibrate about fixed positions

closely packed

accept regular

gas
particles move randomly

accept particles move faster

accept freely for randomly

far apart

(b) amount of energy required to change the state of a substance from liquid to gas (vapour)

unit mass / 1 kg

dependent on first marking point

41400 or 4.14 × 104

correct substitution of

0.018 × 2.3 × 106 gains 1 mark

(d)AB
changing state from solid to liquid / melting

at steady temperature

dependent on first AB mark

BC
temperature of liquid rises

until it reaches boiling point

dependent on first BC mark

[12]

Q5.

(a) density = mass / volume

(b) any two from:

•no forces shown between spheres

•atoms / molecules / ions are not solid spheres

•not all the same size.

(so) the (average) speed of the particles increases

(so there are) more frequent collisions with the wall of the container

which apply a greater force on wall of container (so pressure rises)

[7]

Q6.

(a)any two from:

• water evaporates

accept steam / water vapour for water molecules

accept water turns to steam

• water molecules / particles go into the air

• mirror (surface) is cooler than (damp) air

accept the mirror / surface / glass is cold

• water molecules / particles that hit the mirror lose energy

accept water molecules / particles that hit the mirror cool down

• cooler air cannot hold as many water molecules / particles

(causes) condensation (on the mirror)

accept steam changes back to water (on the mirror)

or
particles move closer together

(b) mirror (surface) is warm

mirror is heated is insufficient

(rate of) condensation reduced

accept no condensation (happens)

[5]

GCSE Physics Revision: 3) Particle Model V1

Examiner reports

Q2.

(a)Most students correctly selected water as storing the most energy.

(b)Whilst most students correctly chose the water-filled heater, many students failed to identify the highest power output as the reason, despite the stem of the question stating that the power output was shown. Many students answered in terms of it having the most energy. Some students just gave the heater as being a radiator, rather than naming it, which could not be credited. Students should be encouraged to use the language given in the question.

(c)Almost a third of students gained full marks for this question. Students who presumably did not have a calculator often gave an incorrect number of zeros, but had attempted to use the correct equation.

Q3.

(a) (i)Students found great difficulty in drawing a representation of a liquid - many of the diagrams looking like the structure of a gas rather than a liquid.

(ii)A poorly answered question, with only the very best students scoring both marks. Many students simply stated that there were fewer particles in a gas.

(b) (i) Students found difficulty in describing the way in which the motion of the ball bearings was similar to that of the gas particles; the difficulty was often with the language rather than the science.

(ii)Some students referred to the ball bearings in the model instead of to the particles in the gas. Some students simply said that the particles moved ‘more’. There were many students who failed to attempt this question.

Q6.

(a) This question discriminated well, with the best students scoring all three marks. However, there was much confusion about terminology with the terms condensation, convection and evaporation apparently interchangeable in many answers. The most common way of gaining a mark was to say that condensation was occurring. The verb “to condensate” was almost universal.

(b) Most students realised that condensation would not take place, although condensation followed by evaporation from the mirror surface was common. Many thought that warm air was “attracted” to a cold surface. Others did not state that the mirror was warm and simply repeated the “heated mirror” from the stem of the question. As in part (a) the meaning of “evaporation” and “condensation” was not clear.