A waste heat exchanger is used to absorb the energy from the complete combustion of hydrogen sulfide gas. What volume of water undergoing a temperature change of 64 C is required to absorb all of the energy from the burning of 15 kg of hydrogen sulfide?
What you're missing is the heat of combustion of H2S. The source below says-519 kJ/mol. (15 kg H2S) x (1000 g/kg) / (34.0814 g/mol) x (519 kJ/mol) = 228424 kJ Specific heat of water is 4.19 kJ/kg degC. (228424 kJ) / (4.19 kJ/kg degC) / (64 degC) = 851.82 kg H2O ≈ 850 L H2O