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Specific Heat Capacity and Latent Heat Questions - GCSE standard

Q18.

Kayjay investigated the insulating properties of different materials. The diagram shows some of the equipment used by her.

This is the method she used:

1. Wrap insulating material around the can.

2. Put a fixed volume of boiling water in the can.

3. Place the lid on the top of the can.

4. Measure the time taken for the temperature of the water to decrease by a fixed amount.

5. Repeat steps 1–4 using the same thickness of different insulating materials.

(a) Identify the independent variable and the dependent variable in this investigation.

The independent variable is the type of insulating material.

The dependent variable is the time taken for the water to decrease by a fixed amount.

[2 marks]

(b) Kayjay used two different types of thermometer to measure the temperature changes. The diagram below shows a reading on each thermometer.

(i) What is the resolution of thermometer B?

0.1oC

[1 mark]

(ii) Thermometer A is more likely to be misread. Give one reason why.

The angle that you view the instrument affects your reading (parallax error) so technique and judgement is needed to reading the position of the liquid thread in the thermometer.

OR the level of the liquid may be between lines

OR the number of lines may be miscounted by the experimenter.

Saying it is harder to read or the lines are close together or human error got you no marks.

[1 mark]

(c) For one type of insulating material, the temperature of the water decreased from 85.0 °C to 65.0 °C. The energy transferred from the water was 10.5 kJ. Given that the specific heat capacity of water is 4200 J/kg °C, calculate the mass of water in the can.

ΔT = 85.0 - 65.0 = 20.0  °C

E = 10.5 kJ = 10 500 J

c = 4200 J/kg °C

E = mcΔT

m = E/(cΔT)

m = 10 500/(4200 x 20)

m = 10 500/84 000

m = 0.125 kg

[3 marks]

(d) The table below shows the results for two insulating materials.

Material
Time for temperature to decrease by 20 °C /seconds
X
450
Y
745

 

Explain how these results can be used to compare the thermal conductivity of the two materials.

It takes less timefor material x to change temperature it is therefore conducting heat at a faster rate and is an better conductor than material X. The thermal conductivity of X is therefore higher than the thermal conductivity of Y.

[2 marks]

(9 marks total)