enthalpy

Question 1

Suggest why the second electron affinity of oxygen is positive.

Answer 1

“oxide” ion, O– and electron are both negative hence energy is required to overcome repulsion.

Question 2

Suggest two reasons why standard enthalpy changes of combustion determined experimentally are less exothermic than the calculated theoretical values

Answer 2

Heat released to the surroundings OR Incomplete combustion/reaction

Question 3

State le Chatelier’s principle

Answer 3

The position of equilibrium will shift to minimise the

effect of any change in conditions.