3.1.4 Energetics Application

State the meaning of the term standard enthalpy change of combustion (2)

Enthalpy change when one mole of a substance burns completely in oxygen, with all substances in their standard states

Give one possible reason, other than heat loss, for why calorimetry may show less exothermic values (1)

The combustion may be incomplete

Define the term enthalpy change (1)

Heat energy change at constant pressure

Explain why the value given for O=O bond enthalpy is not a mean value (1)

Oxygen/O2 is the only substance with an O=O bond

Suggest two reasons why the value of enthalpy of combustion is less exothermic than the book value (2)

Heat loss to surroundings/copper/calorimeter, incomplete combustion occurs

Suggest two disadvantages of using a glass beaker on a tripod and gauze in calorimetry (2)

Glass is a poorer conductor than copper, tripod and gauze reduce heat transfer