1. Why the mass of steam formed during condensation is equal to 9H2 While studying about the lower calorific value of fuel the equation is L.C.V.= H.C.V. – heat of steam formed during combustion Now here in the book they have written that, Let ms = mass of steam formed in per kg of fuel = 9H2 Since the amount of heat per kg of steam is the latent heat of vaporization of water corresponding to standard temperature of 15°C, is 2466 kJ/kg, ∴ L.C.V. = H.C.V.- ms X 2466 kJ/kg = H.C.V. - 9H2 X 2466 kJ/kg …(∵ ms = 9H2) What i don't understand is why this ms is equal to 9H2? what is the chemical reaction here? Why this value is considered constant for all fuels? can anyone please explain?