Specific Heat Capacity and Calorimetry - UNSOLVED PRACTICE SET

Q7. Define specific heat capacity and molar specific heat capacity. Write their SI units.

Q8. Distinguish between Cp (specific heat at constant pressure) and Cv (specific heat at constant volume). For which is Cp greater, and why?

Q9. A 500 g piece of aluminium at 100°C is dropped into 1 kg of water at 20°C. Calculate the final temperature. (Specific heat of aluminium = 900 J/kg·K, specific heat of water = 4200 J/kg·K)

Q10. In your school, a student notices that sand on the playground gets very hot in summer while a nearby puddle of water stays relatively cool. Explain using specific heat capacity.

Q11. Define water equivalent. Calculate the water equivalent of a copper calorimeter of mass 200 g. (Specific heat of copper = 400 J/kg·K)

Q12. Why is water used as a coolant in car radiators and nuclear reactors?

Q13. Explain the principle of calorimetry. Discuss:

(i) Specific heat capacity and its physical significance

(ii) Molar specific heat capacity

(iii) The method of mixtures for determining specific heat capacity

(iv) Sources of error in calorimetry experiments

(v) Why the principle of calorimetry is a consequence of conservation of energy

Q14. A copper calorimeter of mass 200 g contains 500 g of water at 20°C. A 300 g block of copper at 100°C is dropped into the calorimeter.

(a) Calculate the final temperature of the mixture. (Specific heat of copper = 400 J/kg·K, water = 4200 J/kg·K)

(b) Calculate the heat lost by the hot copper block.

(c) Calculate the heat gained by the water and calorimeter.

(d) Verify that heat lost equals heat gained.

(e) Discuss what would happen if the calorimeter were not insulated.

Q15. Analyse the following situations using calorimetry principles:

(i) Determining the specific heat capacity of an unknown metal

(ii) Measuring the temperature of a furnace using the method of mixtures

(iii) Designing a solar water heater

For each case, discuss:

(a) The experimental setup

(b) The measurements required

(c) The calculations involved

(d) Sources of error and how to minimise them

Q16. A 50 g bullet moving at 200 m/s strikes a wooden block and gets embedded in it. The block has mass 450 g and is initially at rest.

(a) Calculate the kinetic energy of the bullet before impact.

(b) If 60% of this energy is converted to heat in the bullet, calculate the temperature rise of the bullet. (Specific heat of bullet material = 150 J/kg·K)

(c) If the remaining energy heats the block, calculate the temperature rise of the block. (Specific heat of wood = 1700 J/kg·K)

(d) Verify that energy is conserved in this process.

(e) Discuss why bullets are often made of lead (specific heat = 130 J/kg·K).

Q17. In a school experiment to determine the specific heat capacity of aluminium, students use the following setup:

Mass of aluminium block = 200 g

Mass of water in calorimeter = 400 g

Mass of copper calorimeter = 100 g

Initial temperature of water and calorimeter = 22°C

Initial temperature of aluminium block = 100°C

Final temperature of mixture = 28°C

(a) Calculate the specific heat capacity of aluminium.

(b) Calculate the percentage error if the accepted value is 900 J/kg·K.

(c) List three sources of error in this experiment.

(d) Suggest two improvements to reduce heat loss.

(e) Why is stirring important during the experiment?

Q18. A solar water heater contains 100 kg of water. The solar collector has an area of 4 m² and receives solar radiation at 800 W/m².

(a) Calculate the total solar energy received in 1 hour.

(b) If 40% of this energy is transferred to the water, calculate the temperature rise of the water.

(c) How long will it take to heat the water from 25°C to 60°C?

(d) If the water is replaced by an equal mass of oil (specific heat = 2000 J/kg·K), calculate the new temperature rise in the same time.

(e) Discuss why water is preferred over oil in solar heaters despite oil heating faster.