Answer to Question #209966 in Organic Chemistry for renren

Question

1.    The value of  for the catalytic hydrogenation of ethene to ethane, C2H4 (g) + H2 (g) à C2H6 (g) is _______ J/K.

Answer 1

Given:

Sof(C2H2(g)) = 200.8 J/mol.K

Sof(H2(g)) = 130.58 J/mol.K

Sof(C2H4(g)) = 219.4 J/mol.K

Balanced chemical equation is:

C2H2(g) + H2(g) ---> C2H4(g)

ΔSo rxn = 1×Sof(C2H4(g)) - 1×Sof( C2H2(g)) - 1×Sof(H2(g))

ΔSo rxn = 1×(219.4) - 1×(200.8) - 1×(130.58)

ΔSo rxn = -112.0 J/mol.K