The heat of fusion for lead at 327.0 °C is 22.9 kJ/kg and the specific heat of lead is 0.130 kJ/kg °C. What is the energy needed to melt 100 grams of lead starting at 0 °C?

Question

Quizplus · Accepted Answer

First, we need to calculate the energy needed to raise the temperature of 100 g of lead from 0°C to 327°C:

Q1 = m × c × ΔT
Q1 = 100 g × 0.130 kJ/kg°C × (327°C - 0°C)
Q1 = 4261 kJ

Next, we need to calculate the energy needed to melt the 100 g of lead at 327°C:

Q2 = m × Hf
Q2 = 100 g × 22.9 kJ/kg
Q2 = 2290 kJ

The total energy needed is the sum of Q1 and Q2:
Q = Q1 + Q2
Q = 4261 kJ + 2290 kJ
Q = 6551 kJ

Therefore, the energy needed to melt 100 grams of lead starting at 0°C is 6.54 kJ (Option C).

The Heat of Fusion for Lead at 327