When boiling water, 690 kJ of energy was expended. Find the mass of evaporated water.

The amount of energy spent on water vaporization can be calculated using the formula
Q = L * m, where Q is the consumed amount of thermal energy (Q = 690 kJ = 690 000 J), m is the mass of evaporated water (kg), L is the specific heat of vaporization of water (L = 2.3 * 106 J / kg ).
Let us express and calculate the mass of the evaporated water:
m = Q / L = 690000 / (2.3 * 106) = 0.3 kg = 300 g.
Answer: The mass of evaporated water is 300 g.