During both boiling and evaporation, liquid ethanol is converted into ethanol vapour.
The rate at which the mass of boiling ethanol decreases depends only on the rate at which the ethanol is gaining thermal energy.
The specific latent heat of vaporisation of ethanol is 8.5 × 105 J/kg. Thermal energy is supplied to boiling ethanol by an electrical heater at a rate of 340 W.
Calculate the mass of ethanol that is boiled away in 250 s.
The rate at which the mass of evaporating ethanol decreases depends on other factors.
State two of these factors.
State two other ways in which evaporation is different from boiling.
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.