Question

How much heat is required to melt a 0.430-kg sample of copper that starts at 45.0°C? (Express your answer to three significant figures.)

Answer 1

Melting temperature of copper = 1085 C

Cc = Specific heat capacity of copper = 387 J/kg-C

Lf = Latent heat of fusion of copper = 206 kJ/kg = 206*10^3 J/kg

So energy required to melt copper will be:

Q = Q1 + Q2

Q1 = energy required to raise temperature from 45 C to 1085 C = m*Cc*dT

Q2 = energy required to phase change from solid to liquid = m*Lf

Q = m*Cc*dT + m*Lf

Q = 0.430*387*(1085 - 45) + 0.430*206*10^3

Q = 261646.4 J = 2.62*10^5 J = 262 kJ

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