The diagram below is an energy profile diagram of the reaction R + S →T+U.

 The diagram below is an energy profile

diagram of the reaction R + S →T+U.

The enthalpy change (delta H) of this reaction is

A. -4 kJ mol-1.

B. +4 kJ mol-1.

C. +6kJ mol-1.

D. -6kJ mol-1.

E. +8kJ mol-1.

The correct answer is B. +4kJ mol-1.

Solution: Enthalpy delta H=Heat content of product - Heat content of reactant

Heat content of product is +6

Heat content of reactant is +2

Enthalpy= +6-+2=+4 option B.

SOURCE: NECO CHEMISTRY 2001 QUESTION 24.