Question

Some gun fanciers make their own bullets, which involves melting and casting the lead slugs. How much heat transfer (in J) is needed to raise the temperature and melt 0.650 kg of lead, starting from 21.0°C

Answer 1

Energy required to melt lead will be given by:

Q = Q1 + Q2

Q1 = energy required to increase temperature from 21 C to melting temperature = m*C*dT

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

m = mass of lead = 0.650 kg

C = Specific heat capacity of lead = 128 J/kg-C

Tf = melting temperature of lead = 327.0 C

dT = 327.0 - 21.0 = 306.0 C

Lf = latent heat of fusion of lead = 24.5*10^3 J/kg

So,

Q = Q1 + Q2 = m*C*dT + m*Lf

So,

Q = 0.650*128*306.0 + 0.650*24.5*10^3

Q = 41384.2 J

Q = 4.14*10^4 J

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