Ncert Exercises & Solutions

Enthalpy is an extensive property. In general, if enthalpy of an overall reaction A $\to$ B along one route is $∆_{r} H$ and $∆_{r} H_{1}, ∆_{r} H_{2}, ∆_{r} H_{3} . . .$ represent enthalpies of intermediate reactions leading to product B. What will be the relation between $∆_{r} H$ overall reaction and $∆_{r} H_{1}, ∆_{r} H_{2} . . . .$ etc for intermediate reactions.

In general, if enthalpy of an overall reaction

A \to B

along one route is

∆_{r} H

and

∆_{r} H_{1}, ∆_{r} H_{2}, ∆_{r} H_{3} . . . . . .

representing enthalpies of reaction leading to same product B along another route, then we have

∆_{r} H = ∆_{r} H_{1} + ∆_{r} H_{2} + ∆_{r} H_{3} . . . . . . . . .