To convert water into steam, 200 kJ of heat was consumed. Determine the initial mass of water

To convert water into steam, 200 kJ of heat was consumed. Determine the initial mass of water if its initial temperature was 40 degrees?

Initial data: Q (consumed amount of heat) = 200 kJ = 200 * 10 ^ 3 J; t0 (initial water temperature) = 40 ºС.

Constants: C (specific heat) = 4200 J / (kg * K); L (specific heat of vaporization) = 2300 * 10 ^ 3 J / kg; tboil (boiling point) = 100 ºС.

We calculate the initial mass of water from the following expression:

Q = Q1 + Q2 = C * m * (tboil – t0) + L * m = m * (C * (tboil – t0) + L).

m = Q / (C * (tboil – t0) + L).

m = 200 * 10 ^ 3 / (4200 * (100 – 40) + 2300 * 10 ^ 3) = 0.078 kg = 78 g.