Question

Calculate the standard enthalpy of the reaction,

2C_(graphite) + 3H_2(g)  → C₂H₆, ΔH⁰ = ? 

From the following ΔH⁰ values :

(a) C₂H_6(g) + \(\frac{7}{2}\)O_2(g) → 2CO_2(g) + 3H₂O_(I). ΔH⁰ = -1560 kJ

(b) H₂(g) + \(\frac{1}{2}\)O_2(g) → H₂O_(I). ΔH⁰ = -285.8 kJ

(c) C_(graphite) + O_2(g)  → CO_2(g).ΔH⁰ = -393.5 kJ.

Answer 1

Given :

The required reaction is the formation of C₂H_6(g).

 C₂H_6(g) + \(\frac{7}{2}\)O_2(g) → 2CO_2(g) + 3H₂O_(I). ΔH⁰ = -1560 kJ

∴ Standard enthalpy of formation of C₂H₆ = -84.4 kJ mol^-1.