Question

In a reaction $a + b \rightleftharpoons c + d$ the change in enthalpy is –10 kcal. If heat is added to the system in which direction the reaction would proceed?

Answer 1

"Consider the reaction with enthalpy: 10 kcal

$a\quad +\quad b\quad \rightarrow \quad c\quad +\quad d$

The -ve sign indicates that the reaction is exothermic

If heat is added to the system the excess of heat will definitely release then products occur at a lower energy and the reactants occur at a higher energy. Thus, the reactions proceeds towards the forward direction.

If the value is of positive then the reaction is endothermic reaction."

Answer 2

Answer:

The change in Gibbs free energy associated with a chemical reaction is a useful indicator of whether the reaction will proceed spontaneously. When the free energy is negative, the reaction will be spontaneous.

ΔH=−150 Kcal mol

−1

ΔS=−7.2 cal mol

−1

K

−1

Gibb's free energy equation is

ΔG=ΔH−TΔS

ΔG=(−15×1000)−300×(−7.2)

ΔG=−12.8 Kcal$$

Above reaction will be spontaneous as the free energy is negative.

Hence, the correct option is A