Question

Which of the following statements is correct for the
spontaneous adsorption of a gas ? [2014]
(a) ∆S is negative and, therefore, ∆H should be highly
positive
(b) ∆S is negative and therefore, ∆H should be highly
negative
(c) ∆S is positive and, therefore, ∆H should be negative
(d) ∆S is positive and, therefore, ∆H should also be highly
positive

Answer 1

Answer:

According to Gibbs equation, for a reaction to be spontaneous

∆G = ∆H - T∆S

∆G value should be negative

Now, consider the points

(a) ∆S is negative and, therefore, ∆H should be highly positive - it will make the value of ∆G +ve

(b) ∆S is negative and therefore, ∆H should be highly negative - it will make ∆G - ve if magnitude of H > TS

(c) ∆S is positive and, therefore, ∆H should be negative - it makes the value of ∆G - ve

(d) ∆S is positive and, therefore, ∆H should also be highly positive - makes the value of ∆G +ve

therefore option B and C Would be correct