Question

Calculate the value of ΔG∘rxnΔGrxn∘ for the following reaction at 296 K. Ka = 2.9 × 10–8 and assume Ka does not change significantly with temperature. $$HClO(aq)+H2O(l) HClO−(aq)+H3O+(aq)

Answer 1

Answer:

$\Delta G_{rxn}=42.7\frac{kJ}{mol}$

Explanation:

In this case, for the dissociation of hypochlorous acid, we know that the acid dissociation constant (Ka) is 2.9x10⁻⁸, which is related with the Gibbs free energy as shown below:

$\Delta G_{rxn}=-RTln(K)$

But in this case K is just Ka, therefore, at 296 K, it turns out:

$\Delta G_{rxn}=-8.314\frac{J}{mol*K}*296K*ln(2.9x10^{-8})\\\\\Delta G_{rxn}=42.7\frac{kJ}{mol}$

Such result, means that the reaction is nonspontaneous at the given temperature, it means it is not favorable (not easily occurring).

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