A student carried out a laboratory experiment to determine the enthalpy change when a sample of ethanol was burned. The heat produced was used to warm some water in a copper calorimeter. Deduce reasons why the student’s value for the standard enthalpy of combustion of ethanol is different from a Data Book value of –1279 kJ mol–1.

The OCR A Chemistry specification splits the content into 6 modules:

(1) Development of practical skills in chemistry (2) foundations in chemistry (3) Periodic table and energy (4) Core organic chemistry (5) Physical chemistry and transition metals (6) Organic chemistry and analysis.