# Water at 20 degrees is cooled into ice, which is cooled to -15 degrees how much heat is released

Water at 20 degrees is cooled into ice, which is cooled to -15 degrees how much heat is released by a mass of water 1 kg.

t1 = 20 ° C.

t2 = 0 ° C.

t3 = – 15 ° C.

Cl = 2100 J / kg * ° C.

Cw = 4200 J / kg * ° C.

q = 3.3 * 105 J / kg.

m = 1 kg.

Q -?

To obtain ice from water, it must first be cooled to the crystallization temperature, which for water is t2 = 0 ° C. At this temperature, transfer from a liquid state to a solid one and cool the resulting ice to a temperature of t3 = – 15 ° C.

Q = Q1 + Q2 + Q3.

Q1 = Sv * m * (t1 – t2).

Q1 = 4200 J / kg * ° C * 10 kg * (20 ° C – 0 ° C) = 84000 J.

Q2 = q * m.

Q2 = 3.3 * 105 J / kg * 1 kg = 330,000 J.

Q3 = Сл * m * (t2 – t3).

Q3 = 2100 J / kg * ° C * 1 kg * (0 ° C – (-15 ° C)) = 31500 J.

Q = 84000 J + 330,000 J + 31500 J = 445500 J.

Answer: when water turns into ice, Q = 445500 J of thermal energy will be released.

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