What amount of heat is given off to the surrounding space by 500 g of water when it cools from 100 ° C to 80 ° C?

Initial data: m (mass of chilled water) = 500 g = 0.5 kg; tн (initial water temperature) = 100 ºС; tк (final temperature of water cooling) = 80 ºС.
Reference values: C (specific heat of water) = 4200 J / (kg * K).
The amount of heat that water will give to the surrounding space is calculated by the formula: Q = C * m * (tн – tк).
Calculation: Q = 4200 * 0.5 * (100 – 80) = 4200 * 0.5 * 20 = 42000 J = 42 kJ.
Answer: When it cools down, water will give 42 kJ of heat to the surrounding space.