entropy change question :)

Question

Use each equation to predict whether the relative entropy change is S_products > S_reactants or S_products < S_reactants and whether ΔS > 0 or ΔS < 0 for the chemical reaction represented. Justify your answer in each case.

a. 2NH₃(g)→N₂(g) + 3H₂(g) (3 point)

b. 2Al(s) + 3F₂(g)→2AlF₃(s) (3 point)

Answer 1

a. 2NH₃(g)→N₂(g) + 3H₂(g) (3 point)

S products > S reactants because there are more moles of gas on the product side (4 mol vs. 2 mol)

∆S is > 0 because 4 - 2 = 2 which is positive change

b. 2Al(s) + 3F₂(g)→2AlF₃(s) (3 point)

S products < S reactants because gases have more entropy than solids and you have 3 moles of gas on the reactant side and none on the product side.

∆S < 0 because 0 - 3 = -3 which is less than 0 so is negative change