If C (diamond) → C(graphite) + X kJ mol^(-1) C(diamond) + O2(g) → CO2(g) + Y kJ mol^(-1)

Question

If C (diamond) \(\rightarrow \mathrm{C}\) (graphite) \(+\ \mathrm{X} \ \mathrm{kJ} \mathrm{mol}^{-1}\)

\(\mathrm{C}(\text { diamond })+\mathrm{O}_{2}(\mathrm{g}) \rightarrow \mathrm{CO}_{2}(\mathrm{~g})+\mathrm{Y} \mathrm{~kJ} \mathrm{~mol}^{-1}\)

\(\mathrm{C} \text { (graphite) }+\mathrm{O}_{2}(\mathrm{g}) \rightarrow \mathrm{CO}_{2}(\mathrm{~g})+\mathrm{Z\ kJ} \mathrm{~mol}^{-1}\)

At constant temperature. Then

(1) X = Y + Z

(2) -X = Y + Z

(3) X = -Y + Z

(4) X = Y - Z

Answer 1

Correct option is (4) X = Y - Z 

\(C(\text{diamond}) + O_2(g) → CO2(g) ; \triangle H_1 = –Y \ kJ \ mol^{–1} \) 

\(CO_2(g) → C(\text{graphite}) + O_2(g) ; \triangle H_2 = Z \ kJ \ mol^{–1}\)

\(C(\text{diamond}) → C(\text{graphite}) ; \triangle H_3 =\ –Y + Z\)    

– X = – Y + Z 

X = Y – Z