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

Let’s compose the equality: mk * qk = L * m2 + Sv * m1 * (tboil – tn), whence mk = (L * m2 + Sv * m1 * (tboil – tn)) / qk.
Constants and variables: L – heat of steam. (L = 2.3 * 10 ^ 6 J / kg); m2 is the mass of vapor. water (m2 = 25 kg); Cw – heat capacity (Cw = 4200 J / (kg * K)); m1 is the total mass (m1 = 5 kg); tboil – temp. boiling (boiling point = 100 ºС); tн – out. pace. (t0 = 20 ºС); qk – heat of combustion. kerosene (qk = 4.6 * 10 ^ 7 J / kg).
Calculation: mk = (2.3 * 10 ^ 6 * 2 + 4200 * 5 * (100 – 20)) / (4.6 * 10 ^ 7) = 0.1365 kg (136.5 g).