Question

what should be the sign of Entropy change

Answer 1

where the sign of ΔG depends on thesigns of the changes in enthalpy (ΔH) and entropy (ΔS). The sign of ΔG willchange from positive to negative (or vice versa) where T = ΔH/ΔS. In cases where ΔG is: negative, the process is spontaneous and may proceed in the forward direction as written.

Answer 2

If the reaction involves multiple phases, the production of a gas typically increases the entropy much more than any increase in moles of a liquid or solid. The reactant side contains only one mole where the product side has six moles produced. The was also a gas produced. Thechange in entropy will be positive.