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3.1 Particle model of matter - High demand – Questions

Q1. According to kinetic theory, all matter is made up of small particles. The particles are constantly moving.

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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(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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(Total 8 marks)

Q2. 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?

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(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.

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(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.

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(Total 7 marks)

Q3. The particle model can be used to explain the properties of gases.

(a) Describe the direction of motion of the particles in a gas.

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(b) Explain why heating a gas increases the average speed of the gas particles.

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(c) Water can exist as either a liquid or a gas at 100 °C.

Explain why a mass of gaseous water at 100 °C contains more energy than an

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equal mass of liquid water at 100 °C.

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(d) Water vapour is a gas. Gases change state when they cool.

The figure below shows condensation on a cold bathroom mirror.

© Dwight Eschliman/Getty Images

A volume of 2.5 × 10–5 m3 of condensation forms on the mirror.

Density of water = 1000 kg / m3

Specific latent heat of vaporisation of water = 2.26 × 106 J / kg.

Calculate the energy released when the condensation forms.

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Energy released = _______________________ J

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(5)

(e) Central heating boilers burn gas and use the energy released to heat water.

Modern condensing central heating boilers take advantage of the energy that is released when water condenses.

Waste water vapour produced when the water is heated in the boiler is used to preheat the cold water entering the boiler.

Give some of the arguments in favour of condensing boilers compared to older non-condensing boilers.

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(Total 15 marks)

Q4. A student investigated the evaporation of three different liquids using the apparatus shown.

Identical pieces of cotton wool were soaked in one of three liquids, A, B or C, that have different boiling points. The same volume of liquid, at the same starting temperature, was used each time.

The temperature of the cotton wool was measured during a ten minute period.

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The results are shown on Graph 1.

(a) Which liquid has the lowest boiling point?

Explain your choice.

Liquid __________

Explanation _________________________________________________________

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(b) Room temperature is 20 °C.

The line for liquid C reached a lower limit of 7 °C.

Explain why the temperature did not fall below 7 °C.

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(1)

(c) Graph 2 shows the distribution of energy among particles in a liquid.

Explain, in terms of the particles in a liquid, why evaporation causes cooling.

You may use information from Graph 2 to help you with your answer.

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(Total 7 marks)

Q5. An athlete runs in a marathon race. As he runs, his body gets hotter.

His body produces sweat to help him cool down.

(a) Explain in terms of particles, how sweating helps the athlete to cool down.

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(b) At the end of the race, the athlete is covered with a ‘space blanket’ made from shiny foil to prevent him from cooling too quickly.

© Fuse/Thinkstock

He wraps the space blanket around his body to reduce energy transfer to the surroundings.

How does the space blanket reduce energy transfer to the surroundings?

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(Total 7 marks)

Q6. The figure below shows a cool box.

A cool box is used to keep food colder than the surroundings. The cool box consists of plastic walls with a layer of polyurethane foam between them.

(a) The polyurethane foam has a low U-value.

Why does the polyurethane foam need to have a low U-value?

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(b) The polyurethane foam contains air bubbles.

Explain how the air bubbles reduce energy transfer through the walls of the cool box.

You should refer to the processes of energy transfer in your answer.

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(c) An ice-pack can be placed inside the cool box. An ice-pack contains a material with a very high specific heat capacity. The ice-pack is frozen in a freezer and cooled to –18 °C before being put in the cool box.

The ice-pack keeps the contents of the cool box cooler than the surroundings for a long time.

Describe how.

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(Total 7 marks)

Q7. The diagram shows a type of electric immersion heater in a hot water tank. These hot water tanks are normally found in airing cupboards.

Information on the immersion heater states:

230 V 10 A

(a) Immersion heaters for hot water tanks often have a switch on them labelled bath or sink. The bath position of the switch has both parts of the immersion heater elements in the circuit. The sink position has only the short heater element in the circuit.

(i) Explain why the hot water outlet is at the top of the tank, and the cold water inlet is at the bottom of the tank.

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(ii) Explain how the sink position for the immersion heater is able to save energy.

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(b) The copper tank is surrounded by plastic foam to minimise energy loss.

Explain why a pale, shiny surface to the foam also helps to minimise energy loss.

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(Total 6 marks)

Q8. The table gives information about some methods of conserving energy in a house.

Conservation method Installation cost in £

Annual saving on energy bills in £

Cavity wall insulation 500 60

Hot water tank jacket 10 15

Loft insulation 110 60

Thermostatic radiator valves

75 20

(a) Explain which of the methods in the table is the most cost effective way of saving energy over a 10 year period. To obtain full marks you must support your answer with calculations.

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(b) Describe what happens to the energy which is 'wasted' in a house.

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(Total 5 marks)

Q9. The diagram below shows a house which has not been insulated. The cost of the energy lost from different parts of the house during one year is shown on the diagram.

(a) The total cost of the energy lost during one year is £1000.

(i) What is the cost of the energy lost through the floor?

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(ii) Suggest one way of reducing this loss.

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(b) The table below shows how some parts of the house may be insulated to reduce energy losses. The cost of each method of insulation is also given.

WHERE LOST COST OF ENERGY LOST PER YEAR (£)

METOD OF INSULATION

COST OF INSULATION (£)

roof 250 fibre-glass in loft 300

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walls 350 foam filled cavity 800

windows 100 double glazing 4500

doors 150 draught proofing 5

(i) Which method of insulation would you install first? Explain why.

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(ii) Which method of insulation would you install last? Explain why.

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(Total 9 marks)

Q10. (a) The table gives information about some ways of reducing the energy consumption

in a house.

Method of reducing energy consumption

Installation cost in £

Annual saving on energy bills in £

Fit a new hot water boiler 1800 200

Fit a solar water heater 2400 100

Fit under floor heating 600 50

Fit thermostatic radiator valves 75 20

Which way of reducing energy consumption is most cost effective over a 10-year period?

To obtain full marks you must support your answer with calculations.

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(b) Explain why using an energy-efficient light bulb instead of an ordinary light bulb reduces the amount of carbon dioxide emitted into the atmosphere.

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(Total 5 marks)

Q11. (a) The diagram shows how much heat is lost each second from different parts of an

uninsulated house.

(i) Each year, the house costs £760 to heat.

How much money is being wasted because of heat lost through the roof?

Show clearly how you work out your answer.

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(ii) Insulating the loft would cut the heat lost through the roof by 50 %.

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The loft insulation has a payback time of years.

How much did the loft insulation cost to buy?

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Cost of loft insulation = £ _________________________ (1)

(b) What happens to the wasted energy?

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(Total 4 marks)

Q12. An electric immersion heater is used to heat the water in a domestic hot water tank. When the immersion heater is switched on the water at the bottom of the tank gets hot.

(a) Complete the following sentence.

The main way the energy is transferred through the copper wall of the water tank is

by the process of ________________________________________ . (1)

(b) The immersion heater has a thermostat to control the water temperature.

When the temperature of the water inside the tank reaches 58°C the thermostat switches the heater off. The thermostat switches the heater back on when the temperature of the water falls to 50°C.

Graph A shows how the temperature of the water inside a hot water tank changes with time. The tank is not insulated.

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Time in hours

(i) The temperature of the water falls at the fastest rate just after the heater switches off.

Explain why.

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(ii) To heat the water in the tank from 50°C to 58°C the immersion heater transfers 4032 kJ of energy to the water.

Calculate the mass of water in the tank.

Specific heat capacity of water = 4200 J/kg°C

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Mass = _______________________________ kg (3)

(iii) An insulating jacket is fitted to the hot water tank.

Graph B shows how the temperature of the water inside the insulated hot water tank changes with time.

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Time in hours

An insulating jacket only costs £12.

By comparing Graph A with Graph B, explain why fitting an insulating jacket to a hot water tank saves money.

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(Total 9 marks)

Q13. A student used the apparatus in Figure 1 to obtain the data needed to calculate the specific heat capacity of copper.

Figure 1

The initial temperature of the copper block was measured.

The power supply was switched on.

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The energy transferred by the heater to the block was measured using the joulemeter.

The temperature of the block was recorded every minute.

The temperature increase was calculated.

Figure 2 shows the student’s results.

Figure 2

Energy transferred to copper block in joules

(a) Energy is transferred through the copper block.

What is the name of the process by which the energy is transferred?

Tick ( ) one box.

Conduction

Convection

Radiation

(1)

(b) Use Figure 2 to determine how much energy was needed to increase the temperature of the copper block by 35 °C.

_________________ joules (1)

(c) The copper block has a mass of 2 kg.

Use your answer to part (b) to calculate the value given by this experiment for the

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specific heat capacity of copper. Give the unit.

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Specific heat capacity = ______________________________ (3)

(d) This experiment does not give the correct value for the specific heat of copper.

Suggest one reason why.

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(Total 6 marks)

Q14. A student investigated the cooling effect of evaporation. She used the equipment in Figure 1 to measure how the temperature of three different liquids changed as the liquids evaporated.

Figure 1

(a) The temperature and volume of each liquid was the same at the start of the investigation.

State one further control variable in this investigation.

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(b) Give two advantages of using dataloggers and temperature probes compared to

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using the thermometer shown in Figure 2.

Figure 2

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(c) The student’s results are shown in Figure 3.

Figure 3

(i) Calculate the average rate of temperature decrease of liquid C between 0 and 100 seconds.

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Average rate of temperature decrease = __________ °C / s (2)

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(ii) Give one conclusion that can be made about the rate of temperature decrease of all three liquids from the results in Figure 3.

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(iii) Which liquid had the lowest rate of evaporation? Give a reason for your answer.

Liquid ________________________________________________________

Reason _______________________________________________________

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(iv) A second student did the same investigation but using a smaller volume of liquid than the first student.

All other variables were kept the same.

What effect would this have on the results of the second student’s investigation?

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(d) Explain how the evaporation of a liquid causes the temperature of the remaining liquid to decrease.

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(Total 11 marks)

Q15. Figure 1 shows a water distiller which is used to purify water.

Figure 1

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The distiller boils water and then condenses most of the water vapour back to water.

(a) The water distiller is filled with 5.0 kg of water at 20 °C

The specific heat capacity of water = 4 200 J/Kg °C

Calculate the energy needed to raise the temperature of the water to 100 °C

Use the Physics Equations sheet.

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Energy = ____________________ J (3)

Figure 2 shows how the temperature of the water in the distiller changes with time.

Figure 2

(b) Energy is transferred to the water at a constant rate.

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Explain why the graph is a different shape in parts A and B.

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(c) When the water drops to a low level, the heater automatically switches off.

Explain what problem would be caused if the heater did not automatically switch off.

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(d) The distiller is connected to the mains by a three-core cable.

The wires are covered by different coloured insulation.

What colour is the insulation covering each of the wires?

Live wire ____________________

Neutral wire ____________________

Earth wire ____________________ (2)

(e) Which statement gives the purpose of the earth wire?

Tick one box.

It carries an alternating potential difference.

It melts if the current in the circuit is too high.

It provides a connection to complete the circuit.

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It stops the casing of the appliance becoming live.

(1)

(f) The heating element has a power of 2.5 kW

The resistance of the heating element is 17 Ω

Calculate the current in the heating element.

Give your answer to 2 significant figures.

Write any equations that you use.

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Current = ____________________ A (5)

(Total 17 marks)