How much kerosene must be burned in order to heat 5 kg of water at 20 degrees

How much kerosene must be burned in order to heat 5 kg of water at 20 degrees Celsius to a boil and turn 2 kg of it into steam?

Data: m1 (mass of heated water) = 5 kg; m2 (mass of evaporated water) = 2 kg; t0 (initial water temp.) = 20 ºС.

Constants: q (beats heat of combustion of kerosene) = 46 * 10 ^ 6 J / kg; C (specific heat capacity of water) = 4200 J / (kg * K); t (temperature of water boiling) = 100 ºС; L (specific heat of vaporization of water) = 2.3 * 10 ^ 6 J / kg.

The mass of kerosene is determined from the equality: q * m3 = C * m1 * (t – t0) + L * m2.

m3 = (C * m1 * (t – t0) + L * m2) / q = (4200 * 5 * (100 – 20) + 2.3 * 10 ^ 6 * 2) / (46 * 10 ^ 6) = 0.137 kg = 137 g.