What amount of energy will be released by water weighing 5 kg when cooled from 100 to 0 * С?

The amount of heat that water will give to the environment can be calculated using the formula:
Q = C * m * (tc – tn), where Q is the released amount of heat (J), C is the specific heat capacity of water (C = 4200 J / (kg * K)), m is the mass of water (m = 5 kg) , tк – final temperature (tк = 0 ºС), tн – initial temperature (tн = 100 ºС).
Let’s calculate the released amount of energy:
Q = C * m * (tc – tn) = 4200 * 5 * (0 – 100) = -2100000 J = – 2.1 MJ.
Answer: Water will release 2.1 MJ of thermal energy.