Answer to Question #139883 in General Chemistry for Drew

Question

From the following data:

C(graphite) + O2(g) à CO2(g) ΔH°rxn = -393.5 kJ/mol

H2(g) + ½ O2(g) à H2O(l) ΔH°rxn = -285.8 kJ/mol

2C2H6(g) + 7O2(g) à 4CO2(g) + 6H2O ΔH°rxn = -3119.6 kJ/mol



Calculate the enthalpy change for the reaction:

2 C(graphite) + 3H2(g) à C2H6(g) ΔH°rxn = ?

Answer 1

The ΔH°rxn of the formation of C2H6(g)  is obtained as follows.

{2(-393.5) + 3(-285.8) }+ 3119.6 KJ.

=-1644.4+3119.6 KJ

=1475.2 KJ/mol