What amount of heat is required to melt 3kg of ice, which has an initial t = -20C
| September 2, 2021 | education
What amount of heat is required to melt 3kg of ice, which has an initial t = -20C, and heat the resulting water to the boiling point?
Data: m (ice mass) = 3 kg; t (initial ice temperature) = -20 ºС.
Constants: C1 = 2100 J / (kg * ºС); λ = 34 * 10 ^ 4 J / kg; tmelt = 0 ºС; C2 = 4200 J / (kg * ºС); tк = 100 ºС.
1) Ice heating: Q1 = C1 * m * (tboil – t) = 2100 * 3 * (0 – (-20)) = 126000 J.
2) Melting ice: Q2 = λ * m = 34 * 10 ^ 4 * 3 = 102 * 10 ^ 4 J.
3) Heating water to boiling: Q3 = C2 * m * (tc – tmelt) = 4200 * 3 * (100 – 0) = 1260000 J.
4) Required heat: Q = Q1 + Q2 + Q3 = 126000 + 102 * 10 ^ 4 + 1260000 = 2406000 J (2.406 MJ).
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