name: particle model of matter - aston academy gcse physics€¦ · according to kinetic theory,...

Particle Model of MatterHigh Demand Questions

Name: ________________________

Class: ________________________

Date: ________________________

Time: 65 minutes

Marks: 65 marks

Comments:

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In this question you will be assessed on using good English, organising informationclearly and using specialist terms where appropriate.

The information in the box is about the properties of solids and gases.

Solids: • have a fixed shape • are difficult to compress (to squash).Gases: • will spread and fill the entire container • are easy to compress (to squash).

Use your knowledge of kinetic theory to explain the information given in the box.

You should consider:• the spacing between the particles• the movement of individual particles• the forces between the particles.

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(Total 6 marks)

(a) A company is developing a system which can heat up and melt ice on roads in the winter.This system is called ‘energy storage’.

During the summer, the black surface of the road will heat up in the sunshine.

This energy will be stored in a large amount of soil deep under the road surface.Pipes will run through the soil. In winter, cold water entering the pipes will be warmed andbrought to the surface to melt ice.

The system could work well because the road surface is black.

Suggest why.

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(1)

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(b) (i) What is meant by specific latent heat of fusion?

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(2)

(ii) Calculate the amount of energy required to melt 15 kg of ice at 0 °C.

Specific latent heat of fusion of ice = 3.4 × 105 J/kg.

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Energy = ___________________ J

(2)

(c) Another way to keep roads clear of ice is to spread salt on them.When salt is added to ice, the melting point of the ice changes.

A student investigated how the melting point of ice varies with the mass of salt added.

The figure below shows the equipment that she used.

The student added salt to crushed ice and measured the temperature at which the icemelted.

(i) State one variable that the student should have controlled.

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(1)

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(ii) During the investigation the student stirred the crushed ice.

Suggest two reasons why.

Tick ( ) two boxes.

Tick ( )

To raise the melting point of the ice

To lower the melting point of the ice

To distribute the salt throughout the ice

To keep all the ice at the same temperature

To reduce energy transfer from the surroundings to the ice

(2)

(iii) The table below shows the data that the student obtained.

Mass of salt added in grams 0 10 20

Melting point of ice in °C 0 -6 -16

Describe the pattern shown in the table.

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(1)

(d) Undersoil electrical heating systems are used in greenhouses. This system could also beused under a road.

A cable just below the ground carries an electric current. One greenhouse system has apower output of 0.50 kW.

Calculate the energy transferred in 2 minutes.

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Energy transferred = ___________________ J

(3)

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(e) In this question you will be assessed on using good English, organising informationclearly and using specialist terms where appropriate.

A local council wants to keep a particular section of a road clear of ice in the winter.

Describe the advantages and disadvantages of keeping the road clear of ice using:

• energy storage

• salt

• undersoil electrical heating.

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(6)

(Total 18 marks)

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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 andmovement of their particles.

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(4)

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

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(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.

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Energy required = __________________ J

(2)

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(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 _________________________________________________________

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Section BC _________________________________________________________

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(4)

(Total 12 marks)

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A student wants to calculate the density of the two objects shown in the figure below.

© Whitehoune/iStock/Thinkstock, © Marc Dietrich/Hemera/Thinkstock

Describe the methods that the student should use to calculate the densities of the two objects.

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(Total 6 marks)

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According to kinetic theory, all matter is made up of small particles. The particles are constantlymoving.

Diagram 1 shows how the particles may be arranged in a solid.

Diagram 1

(a) One kilogram of a gas has a much larger volume than one kilogram of a solid.

Use kinetic theory to explain why.

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(4)

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(b) Diagram 2 shows the particles in a liquid. The liquid is evaporating.

Diagram 2

(i) How can you tell from Diagram 2 that the liquid is evaporating?

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(ii) The temperature of the liquid in the container decreases as the liquid evaporates.

Use kinetic theory to explain why.

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(3)

(Total 8 marks)

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A student investigated how the pressure of a gas varied with the volume of the gas.

The mass and temperature of the gas were constant.

Figure 1 shows the equipment the student used.

Figure 1

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(a) What is the resolution of the syringe?

____________________ cm3

(1)

The student compressed the gas in the syringe and read the pressure from the pressure gauge.

Figure 2 shows the student's results.

Figure 2

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(b) What conclusion can the student make from the data in Figure 2?

Use data from Figure 2 in your answer.

Give the reason for your answer.

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(3)

(c) Explain why the pressure in the gas increases as the gas is compressed.

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(4)

(Total 8 marks)

The figure below shows a balloon filled with helium gas.

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(a) Describe the movement of the particles of helium gas inside the balloon.

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(2)

(b) What name is given to the total kinetic energy and potential energy of all the particles ofhelium gas in the balloon?

Tick one box.

External energy

Internal energy

Movement energy

(1)

(c) Write down the equation which links density, mass and volume.

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(d) The helium in the balloon has a mass of 0.00254 kg.

The balloon has a volume of 0.0141 m3.

Calculate the density of helium. Choose the correct unit from the box.

m3 / kg kg / m3 kg m3

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Density = __________________ Unit _________

(3)

(Total 7 marks)

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Mark schemes

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Marks awarded for this answer will be determined by the Quality of Written Communication(QWC) as well as the standard of the scientific response. Examiners should also apply a ‘best-fit’approach to the marking.

0 marksNo relevant content.

Level 1 (1–2 marks)Considers either solid or gas and describes at least one aspect of the particles.

or

Considers both solids and gases and describes an aspect of each.

Level 2 (3–4 marks)Considers both solids and gases and describes aspects of the particles.

or

Considers one state and describes aspects of the particles and explains at least one of theproperties.

or

Considers both states and describes an aspect of the particles for both and explains aproperty for solids or gases.

Level 3 (5–6 marks)Considers both states of matter and describes the spacing and movement / forces betweenthe particles. Explains a property of both solids and gases.

examples of the points made in the response

extra information

Solids

• (particles) close together• (so) no room for particles to move closer (so hard to compress)• vibrate about fixed point• strong forces of attraction (at a distance)• the forces become repulsive if the particles get closer• particles strongly held together / not free to move around (shape is fixed)

any explanation of a property must match with the given aspect(s)of the particles.

Gases

• (particles) far apart• space between particles (so easy to compress)• move randomly• negligible / no forces of attraction• spread out in all directions (to fill the container)

[6]

1

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(a) (black) is a good absorber of (infrared) radiation12

(b) (i) amount of energy required to change (the state of a substance) from solid toliquid (with no change in temperature)

melt is insufficient1

unit mass / 1kg1

(ii) 5.1 × 106 (J)

accept 5 x 106

allow 1 mark for correct substitution ie E = 15 × 3.4 × 105

2

(c) (i) mass of ice

allow volume / weight / amount / quantity of ice1

(ii) to distribute the salt throughout the ice1

to keep all the ice at the same temperature1

(iii) melting point decreases as the mass of salt is increased

allow concentration for mass

accept negative correlation

do not accept inversely proportional1

(d) 60 000 (J)

accept 60 KJ

allow 2 marks for correct substitution ie E = 500 × 2.0 × 60

allow 2 marks for an answer of 1000 or 60

allow 1 mark for correct substitution ie

E = 500 × 2.0 or 0.50 × 2.0 × 60

allow 1 mark for an answer of 13

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(e) Marks awarded for this answer will be determined by the Quality of Communication(QC) as well as the standard of the scientific response. Examiners should also applya ‘best-fit’ approach to the marking.

0 marksNo relevant content

Level 1 (1–2 marks)There is an attempt at a description of some advantages or disadvantages.

Level 2 (3–4 marks)There is a basic description of some advantages and / or disadvantages for some ofthe methods

Level 3 (5–6 marks)There is a clear description of the advantages and disadvantages of all the methods.

examples of the points made in the response

extra information

energy storage

advantages:

• no fuel costs• no environmental effects

disadvantages:

• expensive to set up and maintain• need to dig deep under road• dependent on (summer) weather• digging up earth and disrupting habitats

salt spreading

advantages:

• easily available• cheap

disadvantages:

• can damage trees / plants / drinking water / cars• needs to be cleaned away

undersoil heating

advantages:

• not dependent on weather• can be switched on and off

disadvantages:

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• costly• bad for environment

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[18]

(a) solidparticles vibrate about fixed positions

1

3

closely packed

accept regular1

gasparticles move randomly

accept particles move faster

accept freely for randomly1

far apart1

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

1

unit mass / 1 kg

dependent on first marking point1

(c) 41000 or 4.1 × 104 (J)

accept

41400 or 4.14 × 104

correct substitution of

0.018 × 2.3 × 106 gains 1 mark2

(d) ABchanging state from solid to liquid / melting

1

at steady temperature

dependent on first AB mark1

BCtemperature of liquid rises

1

until it reaches boiling point

dependent on first BC mark1

[12]

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Level 3 (5–6 marks):Clear and coherent description of both methods including equation needed to calculate density.Steps are logically ordered and could be followed by someone else to obtain valid results.

Level 2 (3–4 marks):Clear description of one method to measure density or partial description of both methods. Stepsmay not be logically ordered.

Level 1 (1–2 marks):Basic description of measurements needed with no indication of how to use them.

0 marks:No relevant content.

Indicative content

For both:• measure mass using a balance• calculate density using ρ = m / V

Metal cube:• measure length of cube’s sides using a ruler• calculate volume

Small statue:• immerse in water• measure volume / mass of water displaced• volume of water displaced = volume of small statue

[6]

4

(a) there are strong forces (of attraction) between the particles in a solid

accept molecules / atoms for particles throughoutaccept bonds for forces

1

5

(holding) the particles close together

particles in a solid are less spread out is insufficient1

or

(holding) the particles in a fixed pattern / positions

but in a gas the forces between the particles are negligible

accept very small / zero for negligibleaccept bonds for forces

1

so the particles spread out (to fill their container)

accept particles are not close togethergas particles are not in a fixed position is insufficient

1

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(b) (i) particles are (shown) leaving (the liquid / container)

accept molecules / atoms for particles throughout

accept particles are escapingparticles are getting further apart is insufficient

1

(ii) accept molecules / atoms for particles throughout accept speed / velocity for energy throughout

particles with most energy leave the (surface of the) liquid

accept fastest particles leave the liquid1

so the mean / average energy of the remaining particles goes down1

and the lower the average energy (of the particles) the lower the temperature(of the liquid)

1

[8]

(a) 1 (cm3)1

6

(b) pressure is inversely proportional to volume1

data to prove inversely proportional relationship

eg 8 × 200 = 1600

and 10 × 160 = 1600

if no other marks score allow for 1 mark: as volume decreasespressure increases

2

(c) (as the gas is compressed) the volume of gas decreases1

(so there are) more frequent collisions of gas particles withcontainer walls

1

(and) each particle collision with the wall causes a force1

(so there is a) greater force on walls1

[8]

(a) range of speeds17

moving in different directions

accept random motion1

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(b) internal energy1

(c) density = mass / volume1

(d) 0.00254 / 0.01411

0.181

accept 0.18 with no working shown for the 2 calculation marks

kg / m3

1

[7]

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Examiner reports

A low proportion of students were able to make a relevant comment on the arrangements ofparticles in solids or gases.

Generally, most students made a good attempt at the question, with few students leaving it blank.Most were able to make sensible statements about the spacing and movement of particles insolids and gases, but rather fewer referred to the forces between the particles: fewer stillattempted to use these statements to explain the properties given in the information box.

Too many students simply repeated the information given in the question and weaker studentswrote all they knew, including about particles and their behaviour in a liquid The use of the term‘kinetic theory’ in the question distracted some students into describing conduction andconvection. Others became obsessed with the fact that free electrons make metals goodconductors.

More able students could select the relevant property of particles to explain the macroscopicproperty of solids and gases.

1

(a) Three-quarters of students knew why an energy storage system would work if the roadsurface was black. Many answers stated that ‘black surfaces absorb heat’ rather than‘absorb heat well’.

(b) (i) A quarter of students gave a correct definition of specific latent heat of fusion.However, many incorrect responses referred to melting rather than a change fromsolid to liquid.

(ii) Nearly all students correctly calculated the amount of energy required to melt the ice.

(c) (i) Two-thirds of students correctly stated that the variable to be controlled was mass ofice. The remainder stated that the mass of salt had to be controlled.

(ii) Two-thirds of students correctly ticked two boxes with suggestions as to why thestudent stirred the crushed ice.

(iii) Nearly all students could correctly describe the pattern of how mass of salt added tosome crushed ice affected the melting point of the ice.

(d) Just under half of students scored full marks for a calculation of energy transferred givenvalues of power and time in non-SI units. Conversion from: kW to W; and minutes toseconds, was required. The spread of marks demonstrated this, with a third of studentsdropping one mark.

(e) The Quality of Communication question brought together the elements of the entirequestion and asked for advantages and disadvantages of using energy storage, salt andundersoil heating for keeping a road free from ice in the winter. Most students used theavailable space and many used additional pages.

Three-quarters of students scored four marks or more. Some excellent work was seen, butmany students wasted time by repeating much of what was in the question. Also theyended a very good account with an unnecessary summary. Some very well written workonly addressed either an advantage or a disadvantage of each system.

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(a) Whilst many answers referred to the arrangement of particles in solids and gases, fewerresponses referred to the forces between the particles.

(b) (i) Just under half of the students answered correctly in terms of particles leaving thecontainer / liquid. Other answers seen just referred to the particles ‘rising.’

(ii) Many answers referred to particles needing energy to escape, but often just stated‘gaining energy’, without specifying that they had more energy than the particles thatremained. Very few students gained the second marking point because they did notrefer to “mean / average” energy. A fair number of students gained the third mark bylinking a decrease in energy to the decrease in temperature.

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name: particle model of matter - aston academy gcse physics€¦ · according to kinetic theory,...

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