Question 3
This question is about combustion.
(a) State the meaning of the term standard enthalpy of combustion.
(2)
(b) A student does an experiment to determine the enthalpy of combustion of propan-1-ol (CH3CH2CH2OH, Mr = 60.0).
Combustion of 0.497 g of propan-1-ol increases the temperature of 150 g of water from 21.2 °C to 35.1 °C
Calculate a value, in kJ mol–1, for the enthalpy of combustion of propan-1-ol in this experiment.
The specific heat capacity of water is 4.18 J K–1 g–1
(3)
(c) The enthalpy of combustion determined experimentally is less exothermic than that calculated using enthalpies of formation.
Give one possible reason for this, other than heat loss.
(1)
(Total 6 marks)