Question

S(s)+o2(g)→so2(g), δh∘ = -296.8kjso2(g)+12o2(g)→so3(g) , δh∘ = -98.9kjto calculate δh∘f for h2so4(aq) (in kilojoules per mole).[for h2o(l),δh∘f = -285.8kj/mol]

Answer 1

S(s)+O2(g)→SO2(g), ΔHâ = -296.8kJ SO2(g)+12O2(g)→SO3(g) , ΔHâ = -98.9kJ H2(g) + 1/2 O2 (g) --------> H2O(l)ΔHâf = -285.8kJ SO3(g) + H2O(l) --------> H2SO4, ΔHâ = -227.8 kJ . All above steps are involved in the formation of H2SO4, therefore delta Hf for H2SO4 is [ -296.8+ (-98.9)+ (-285.8) +(-227.8)] = - 909.3 kj/mol The energy required to form 1 mol H2SO4 fom its elements is - 909.3 kj / mol