Problem

Problem

A student wanted to find the enthalpy of combustion of propan-1-ol and collected the following data.
Initial mass of burner and propan-1-ol / g45.65
Final mass of burner and propan-1-ol / g45.05
Mass of water heated / g210
Initial temperature of water / °C23.7
Final temperature of water / °C41.5
Specific heat capacity of water / J K -1 g -14.18
(a) Calculate the amount, in mol, of propan-1-ol burnt. (b) Calculate the heat absorbed, in kJ, by the water. (c) Determine the enthalpy change, in kJ mol-1, for the combustion of one mole of propan-1-ol. (d) Suggest why this value differs from the literature value of -2021 kJ mol-1.
Intuitive explanation

The enthalpy of combustion links the energy released by burning fuel to the temperature rise it causes in water. You'll track three connected quantities: how much fuel burned (from mass loss), how much heat the water absorbed (using q=mcΔTq = mc\Delta T), and finally the energy per mole of fuel. The key is converting between grams of propan-1-ol and moles using its molar mass (60 g/mol), then scaling the total heat energy to a per-mole basis.

Intuitive explanation

The enthalpy of combustion links the energy released by burning fuel to the temperature rise it causes in water. You'll track three connected quantities: how much fuel burned (from mass loss), how much heat the water absorbed (using q=mcΔTq = mc\Delta T), and finally the energy per mole of fuel. The key is converting between grams of propan-1-ol and moles using its molar mass (60 g/mol), then scaling the total heat energy to a per-mole basis.

Browse the problem library