Specific heat capacity

Diagram 1 shows the apparatus a student uses to determine the specific heat capacity of a liquid.

Describe a suitable method the student could use to determine the specific heat capacity of the liquid.

The graph shows the student’s results.

What is happening to the liquid between points P and Q on the graph?

Use the graph to determine the change in temperature of the liquid after 15 minutes of heating.

The power of the heater is 48 W and the mass of the liquid is 0.53 kg.

Calculate the specific heat capacity of the liquid.

specific heat capacity =_........ J / kg °C

The photograph shows a water bath that a technician uses to heat some water.

The water bath is filled with water at an initial temperature of 15C.

Calculate the initial temperature of the water in kelvin.

The technician heats the water to a final temperature of 60C.

Describe how the energy of the water molecules changes as the temperature of the water increases.

The table shows some information about the heating element in the water bath and the heating process.

Calculate the energy transferred by the heating element in the water bath during the heating process.

Calculate the mass of water being heated.

Assume that all the energy is transferred to the thermal store of the water. [for water, specific heat capacity = 4200 J / kgC]

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Some water evaporates as a gas from the water bath.

Describe the arrangement of particles in a gas.

Describe two differences between evaporation and boiling.

The diagram shows some apparatus that can be used to determine the specific heat capacity of water.

Describe how a student could use this apparatus to determine the specific heat capacity of water.

Include details of any additional equipment needed in your answer.

The table shows the student’s results.

Use the student’s results to calculate the specific heat capacity of water.

specific heat capacity of water =_........ J / kg °C

Give two reasons why the energy from the heater is not all retained in the thermal store of the water.

This question is about specific heat capacity.

State what is meant by the term specific heat capacity.

The diagram shows a sample of solid stearic acid being heated in a boiling tube using a water bath.

The mass of stearic acid in the boiling tube is 58 g.

When the boiling tube is placed in the water bath, the temperature of the stearic acid increases from 21 °C to 37 °C. The stearic acid does not melt.

As the temperature of the stearic acid increases, an additional 3500 J of energy needs to be transferred electrically to the water bath.

Using this data, show that the specific heat capacity of the solid stearic acid is approximately 4 J / g °C.

The true value for the specific heat capacity of solid stearic acid is 2.3 J / g °C.

Give a reason for the difference between the value in (i) and the true value.

Concrete on top of buildings can be used to heat water.

The photograph shows a concrete and water heating system being built into the roof of a house.

A scientist wants to determine the specific heat capacity of concrete.

The diagram shows some of the equipment they could use.

Describe a suitable method to find the specific heat capacity of concrete.

Explain the advantage of the concrete having a high specific heat capacity when it is used to heat water in the heating system.

The photograph shows an ice cube placed on a metal tile.

The solid ice cube melts to become liquid water.

Compare the arrangement of particles in a solid with the arrangement of particles in a liquid.

You may draw a diagram to help your answer.

Describe the difference in the movement of particles in a solid compared with the movement of particles in a liquid.

After the ice cube has melted, the liquid water increases in temperature.

The water has a mass of 16 g and a specific heat capacity of 4200 J/kgC.

Calculate the energy transferred to the liquid water as it increases in temperature from 3C to 21C.

This question is about the use of water in central heating systems.

A student does an investigation to find the specific heat capacity of water.

This is the list of equipment they use.

• heater with a power output of 50 W

• power supply

• beaker

• water

• thermometer

• stopwatch

• connecting leads

• balance

Describe an investigation the student could use to find the specific heat capacity of water.

You may draw a diagram to help your answer.

The diagram shows a simplified central heating system viewed from above.

Pipes transport hot water around a house to radiators and back to the boiler.

The boiler heats water from 16C to 65C.

Calculate the energy transferred from the boiler to 75 kg of water to raise the temperature of the water from 16C to 65C.

[for water, specific heat capacity = 4200 J/kgC]

The radiators transfer energy from the water to the air in the house.

The temperature of the water in the heating system decreases by 4C due to heat transferred to the air.

This causes the air in the house to increase in temperature by 15C.

The mass of air in the house and the mass of water in the heating system are approximately the same.

Explain why there is a larger temperature change in the air.

A student heats a sample of water.

The student measures the temperature of the sample of water during heating.

The sample of water has a mass of 0.45 kg.

Calculate the energy required to increase the temperature of the water from 16 °C to 100 °C.

[specific heat capacity of water = 4200 J / kg °C]

The diagram shows the temperature-time graph for the sample of water.

Use the graph to determine the time taken from when the water started to boil to when the water stopped boiling.

time taken =_........ minutes

The heater used to heat the water has a power rating of 2200 W.

Calculate the energy required to boil all of the water.

Give a reason why the liquid water should be stirred during the heating.

When water boils, the liquid water becomes a gas called steam.

Describe the changes in arrangement and motion of the molecules in liquid water and the molecules in steam.

A student uses a small iron nail and a beaker of water to estimate the temperature of a flame. The diagram shows some of the equipment used.

This is the student’s method

• place a thermometer into the beaker of water

• record the temperature of the water

• heat the nail in the flame for a long period of time

• quickly move the nail into the beaker of water

• record the highest temperature of the water

State a safety precaution the student should take.

While in the water, the thermal energy store of the nail decreases and the thermal energy store of the water increases until their temperatures are the same.

The energy lost from the nail is equal to the energy gained by the water.

The table shows the student’s results.

Show that the energy gained by the water is approximately 3000 J.

Calculate the temperature change of the nail.

Give a reason why the calculated temperature change of the nail is lower than the actual temperature change.

The diagram shows the temperature‑time graph for a substance which is heated at a constant rate.

Which section of the graph shows when the substance is melting?

Which section of the graph shows when all the substance is a solid?

Draw particles in the box to show the arrangement of particles when the substance is a gas.

Which of these statements best describes the motion of particles in a gas?

Name a piece of apparatus that could be used to measure the temperature of the substance.

Determine the boiling point of this substance.

The substance has a mass of 1.2 kg.

Calculate the energy required to raise the temperature of the substance from 10C to 37C.

[assume specific heat capacity of substance = 840 J/kgC]

Energy is transferred from the Sun to the Earth.

Nuclear fusion happens in the Sun.

Which energy store of the Sun decreases during nuclear fusion?

How is energy transferred through space from the Sun to the Earth?

Solar panels use energy from the Sun to heat water.

The total area of the solar panels is 15 m².

Each 1.0 m² of the solar panels receives 1000 J of energy per second from the Sun.

Show that the total energy transferred to the solar panels in 2 hours is about 100 MJ.

A mass of 1100 kg of cold water is in the solar panels at an initial temperature of 20C.

Calculate the final temperature of this water after it has been heated by the Sun for 2 hours.

[specific heat capacity of water = 4200 J/kg C]

final temperature _........ C

Give a reason why the actual final temperature of the water will be lower than the calculated value.

The Parker Solar Probe is a spacecraft that was launched in 2018 on a mission to explore the Sun.

The spacecraft is partly covered in tiles.

These tiles are filled with a solid containing small pockets of trapped air.

The outer surface of the tiles is painted white.

These tiles protect the electric circuits in the spacecraft from extreme temperatures.

The diagram shows one of these tiles in cross-section.

Explain why the outer surface of the tile is painted white.

Explain how the small pockets of trapped air help to reduce thermal energy transfer from the outer surface to the inner surface of the tile.

The electric circuits inside the spacecraft are cooled by 4.5 kg of water.

The initial temperature of the water is 35^oC.

The thermal store of the water increases by 210 kJ.

Calculate the final temperature of the water.

[specific heat capacity of water 4200 J/kg^oC]

final temperature _........ ^oC

A student does an investigation to determine the temperature-time graph for water as it changes state from ice to liquid water.

The diagram shows the student’s apparatus.

The ice has an initial temperature of –17 °C.

After 5 minutes, the ice begins to melt.

After a further 6 minutes, all the ice has melted.

The investigation continues for a total time of 20 minutes.

Sketch a graph on the axes to show how the temperature changes with time.

Assume that the rate of energy transfer from the heater to the ice cubes is constant.

Suggest a precaution the student should take to obtain high quality data.

During the experiment the heater transfers 2500 J of energy to the beaker.

The beaker has a specific heat capacity of 880 J / kg °C and a mass of 48 g.

Calculate the increase in the temperature of the beaker.

Stearic acid is a solid at room temperature and melts at a temperature of 69 C.

A student investigates the specific heat capacity of solid stearic acid.

He heats a sample of stearic acid from room temperature using an electrical heater and measures its temperature using a data logger and temperature sensor.

The graph shows his results.

The student starts heating the stearic acid at 130 seconds.

Determine the time it takes to heat the stearic acid until it reaches its melting point.

The stearic acid gains 39 kJ of energy during the time it is heated to its melting point.

Calculate the mean (average) power of the heater.

Give a unit with your answer.

[assume no energy lost to surroundings]

The mass of stearic acid used in the investigation is 0.45 kg.

The stearic acid gains 39 kJ of energy when it is heated to its melting point.

Calculate the specific heat capacity of stearic acid.

You should use data from the graph in your calculation.

specific heat capacity =_........ J/kgC

A dog sits on a water‑filled bag to keep cool.

The table shows some data about the dog and the water in the bag.

The dog sits on the bag for 22 minutes.

Calculate the energy transferred from the dog to the water by heating in 22 minutes.

State an assumption you have made when calculating the energy transferred.

Calculate the temperature of the water after 22 minutes.

temperature =_........ C

Discuss why conduction is the main way that thermal energy is transferred from the dog to the water.