Question

24. Determine A Sºrxn given the following information: Reaction: Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(9) Substance Zn(s) HCl(aq) H2(g) Zn2+(aq) Cl(aq) Sº (J/mol x K) 60.9 56.5 130.58 -106.5 55.10 A) -39.6 J/mol.K B) O J/mol.K C) +39.6 J/mol.K D) -38.2 J/mol.K E) +38.2 J/mol.K

Answer 1

Answer

A) - 39.6 J/ mol K

Explanation

Zn(s) + 2HCl(aq) ------> ZnCl2(aq) + H2(g)

∆S°_rxn = $\sum$nS°(products) - $\sum$mS°(reactants)

n and m are coefficients of products and reactants

= ( 1 × S°(Zn²⁺(aq)) + 2 × Cl^-(aq)) + 1×S°(H2(g))) - ( 1 × S°(Zn(s)) + 2×S°(HCl(aq)))

= ( 1 × -106.5J/mol K + 2× 55.10J/mol K + 1 × 130.58J/mol K) - ( 1× 60.9J/mol K + 2× 56.5J/mol K)

= 134.28J/mol K - 173.9J /mol K

= -39.6J/mol K