200 g of lead is at a temperature of 227 degrees Celsius. The melting point of lead is 327 degrees Celsius

| May 2, 2021 | education

200 g of lead is at a temperature of 227 degrees Celsius. The melting point of lead is 327 degrees Celsius. How much heat is needed to melt lead?

Given: m = 0.2 kg, tn = 227 oC, tm = 327 oC. Find Q.

The required amount of heat is determined as Q = Qn + Qpl, where Qn is the amount of heat required to heat lead to tmelt; Qpl is the amount of heat required to melt lead.
Qn = C * m * (tpl – tn), where C is the heat capacity of lead, J / (kg * oC); m is the mass of lead, kg; tн – initial temperature of lead, оC; tmelt – melting point of lead, oC.
Qp = L * m, where L is the specific heat of fusion of lead, J / kg; m is the mass of lead, kg.
According to the reference book, we find C = 130 J / (kg * oC); L = 25000 J / kg.
Substituting the data, we consider: Qн = C * m * (tpl – tn) = 130 * 0.2 * (327 – 227) = 2600 J; Qp = L * m = 25000 * 0.2 = 5000 J; Q = Qн + Qп = 2600 + 5000 = 7600 J.

Answer: Q = 7600 J.



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