To find out the amount of heat released by 200 ml of water in a glass, we use the formula: Q = Qcool + Qcr = Sv * V * ρw * (t1 – 0) + λw * V * ρw = V * ρw * (Sv * t1 + λw) …
Const: ρw is the density of water in the glass (ρw = 1000 kg / m3); St. – beats. heat capacity of water (Sv = 4.18 * 10 ^ 3 J / (kg * K)); λw – beats heat of crystallization of water (λw = 332.4 * 10 ^ 3 J / kg).
Data: V – volume of water taken (V = 200 ml; in SI system V = 0.0002 m3); t1 – initial temperature (t1 = 20 ºС).
Let’s perform the calculation: Q = V * ρw * (Sv * t1 + λw) = 0.0002 * 1000 * (4.18 * 10 ^ 3 * 20 + 332.4 * 10 ^ 3) = 83.2 * 10 ^ 3 J.
Answer: The water in the glass should release heat in the amount of 83.2 kJ.
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