13 and 33 (b) How much air is needed it' 1 13.10' Calculate the gross and net heating value (kJ/m at STP) of a fuel gas analyzing 80% are -890.4, -1559.9, -2220, -2878.52 kJ/mol, respectively, for methane, ethane, propane, methane, 10% ethane, 6% propane and 4% butane. The standard heats of combustion and butane, and the latent heat of vaporization of water at 298 k is 44.014 kJ/mol. urhon fuels can be produced from methanol by reactions such as the following