When water is heated from 15 to 100 degrees Celsius, its internal energy will increase by 178.8 kJ.

When water is heated from 15 to 100 degrees Celsius, its internal energy will increase by 178.8 kJ. Find the mass of heated water.

Initial data: t1 (water temperature before heating) = 15 ºС; t2 (final heating temperature) = 100 ºС; Q (increase in the internal energy of water) = 178.8 kJ (178.8 * 10 ^ 3 J).

Reference values: Sv (specific heat capacity of water) = 4200 J / (kg * ºС).

We express the mass of heated water from the formula: Q = Cw * m * (t2 – t1), whence m = Q / (Cv * (t2 – t1)).

Calculation: m = 178.8 * 10 ^ 3 / (4200 * (100 – 15)) = 0.5 kg (500 g).

Answer: The mass of heated water is 500 grams.