Thermal energy and specific heat capacity

Sample questions

Original practice questions written in the style of the exam.

1. Question 14 marks

   A $2.0\,\text{kW}$ kettle contains $0.80\,\text{kg}$ of water at $20\,^\circ\text{C}$. Assume no energy is lost to the surroundings.

   Quantity	Value
   specific heat capacity of water	$4180\,\text{J kg}^{-1}\,\text{K}^{-1}$
   specific latent heat of vaporisation of water	$2.26 \times 10^{6}\,\text{J kg}^{-1}$

   (a) Calculate the time taken to bring the water to $100\,^\circ\text{C}$.

   (b) Calculate the further time needed to boil away $0.10\,\text{kg}$ of the water.

   Mark scheme

   • $\Delta E = mc\Delta\theta = 0.80 \times 4180 \times 80 = 2.68 \times 10^{5}\,\text{J}$ (1)
2. Question 24 marks

   A $0.20\,\text{kg}$ copper block at $95\,^\circ\text{C}$ is dropped into $0.30\,\text{kg}$ of water at $20{}^{}$ in an insulated container of negligible heat capacity.