Question

Enthalpy of combustion of CH₄, C₂H₆ and C₃H₈ are – 210, – 370 and –530 kcal/mol respectively. The approximate value of enthalpy of combustion of n-hexane is-

• A. – 1170 $\frac{kcal}{mol}$
• B. – 750 $\frac{kcal}{mol}$
• C. – 1010 $\frac{kcal}{mol}$
• D. – 590$\frac{kcal}{mol}$

Answer 1

Answer: (C)

– 1010 $\frac{kcal}{mol}$

Answer 2

For each – CH₂ the enthalpy of combustion is increased by 160 kcal/mol.

\ D_comb H (C₆H₆) = – 210 – 5 × 160 = – 1010 $\frac{kcal}{mol}$