Given S(s) + O2(g) -> SO2(g), Delta H = -296.8 kJ, and SO2(g) + 1/2 O2(g) -> SO3(g), Delta H = -98.9 kJ, the enthalpy change for S(s) + 3/2 O2(g) -> SO3(g) is

JEE Main levelSingle correct optionDifficulty 2 of 3td080

Given $S (s) + O X_{2} (g) SO X_{2} (g)$ , $Δ H = - 296.8 kJ$ , and $SO X_{2} (g) + \frac{1}{2} O X_{2} (g) SO X_{3} (g)$ , $Δ H = - 98.9 kJ$ , the enthalpy change for $S (s) + \frac{3}{2} O X_{2} (g) SO X_{3} (g)$ is

Adding the two equations cancels

SO X_{2}

and gives the target reaction. By Hess's law

Δ H = - 296.8 + (- 98.9) = - 395.7 kJ