The heat of combustion of ethane gas is 373 kcal/mole. Assuming that 60.0 percent of the heat is useful, how many liters of ethane, measured at standard temperature and pressure, must be burned to convert 50.0 kg of water at 10.0 °C to steam at 100.0 °C? One mole of a gas occupies 22.4 liters at precisely 0 °C and 1 atm.