How much heat is needed to melt 2 kg of lead, which has a temperature of 227 C? The melting point of lead is 327 C, the specific heat is 140 J / kg * C, and the specific heat of fusion is 25 kJ / kg.
Task data: m (mass of taken lead) = 2 kg; t (lead temperature before heating) = 227 ºС.
Constants: according to the condition tmelt (melting temperature) = 327 ºС; С (specific heat) = 140 J / (kg * ºС); λ (specific heat of fusion) = 25 kJ / kg (25 * 10 ^ 3 J / kg).
The amount of heat for smelting lead is determined by the formula: Q = C * m * (tmelt – t) + λ * m.
Calculation: Q = 140 * 2 * (327 – 227) + 25 * 10 ^ 3 * 2 = 78000 J (78 kJ).
Answer: You need 78 kJ of heat.
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