For which of the following reactions...

Question

For which of the following reactions is the value of delta(H)_reaction equal to the delta(H)_final for the products?

a) 2C(s,graphite) + 2H_2(g) --> C_2H_4

b) N_2 (g) + O_2 (g) --> 2NO (g)

c)2H_2 (g) + O_2 (g) --> 2H_2O (l)

d)2H_2 (g) + O_2 --> 2H_2O (g)

e) H_2O (l) + 1/2O_2 (g) -- H_2O_2 (l)

*Please show how you arrived at your answer as clearly as possible.

Thank you.

Answer 1

The ∆Hrxn is the ∆Hformation of products - reactants. To get this to be equal to the ∆H of products, the ∆H formation for the reactants would have to be zero. The only one that satisfies this is (a) because the ∆H formation for C(s, graphite) is zero.