S(s) + 3/2 O2(g) ➞ SO3(g) + 2x KJ SO2(g) + 1/2 O2(g) ➞ SO3(g) + y kJFind the heat of formation of SO2(g) .

Explanation

Reverse the second reaction and change the sign of its enthalpy change: SO3(g) + y kJ → SO2(g) + 1/2 O2(g) Multiply the first reaction by 2 to match the stoichiometry of the oxygen molecules in the reversed second reaction: 2(S(s) + 3/2 O2(g) → SO3(g) + 2x kJ) Add the two reactions together to get the desired reaction: 2(S(s) + 3/2 O2(g) → SO3(g) + 2x kJ) + (SO3(g) + y kJ → SO2(g) + 1/2 O2(g)) The intermediate terms cancel out: 2S(s) + 3O2(g) → 2SO3(g) + 2x kJ + y kJ Simplify the equation: 2S(s) + 3O2(g) → 2SO3(g) + (2x + y) kJ Now, we can isolate the desired reaction and the heat of formation of SO2(g): 2SO3(g) → 2S(s) + 3O2(g) + (2x + y)kJ The heat of the formation of SO2(g) from its elements in their standard states is equal to the value of (2x + y) kJ, hence option C is correct.