A beaker contains a volatile liquid at room temperature. The beaker is placed on a heating plate, and the temperature of the liquid begins to increase.
The liquid is evaporating.
Describe one difference between evaporation and boiling.
State and explain what happens to the rate at which the liquid evaporates as its temperature increases.
After a few minutes, the liquid reaches its boiling point temperature. The liquid continues to gain thermal energy from the heating plate.
State what happens to the temperature of the liquid while it is boiling.
The specific latent heat of vaporisation of the liquid is 1.8 × 106 J/kg. After the liquid reaches its boiling point, it takes 15 minutes15\text{ minutes}15 minutes for 0.12 kg of the liquid to boil away.
Calculate the average rate at which energy is being supplied to the liquid by heating.
528 exam-style questions on CIE IGCSE Physics 2.2 Thermal properties and temperature, covering 2.2.1 Thermal expansion of solids, liquids and gases, 2.2.2a Internal energy and temperature, 2.2.2b Specific heat capacity, 2.2.3a Melting, boiling, condensation and solidification, 2.2.3b Evaporation, and 2.2.3c Cooling by evaporation. Each one has a worked solution and a mark scheme showing where the marks go.