Question

Calculate the standard entropy change for the following reaction at 25 °C. S° values can be found here. mg(oh)2 + 2hcl

Answer 1

Given reaction:

Mg(OH)2(s) + 2HCl(g) → MgCl2(s) + 2H2O(g)

Formula:

ΔS°rxn = ∑nS°(products) - ∑nS°(reactants)

           = [S°(MgCl2) + 2S°(H2O)] -[S°(Mg(OH)2 + 2S°(HCl)]

           = [89.3+2(188.7)] - [63.22+2(186.80] = 29.88 J/K

Thus, the standard entropy change for the reaction is around 30 J/K