A metallurgical technician heats a 1.5 kg solid lead block in a crucible until it melts completely. The starting temperature of the lead is 27∘C27^\circ\text{C}27∘C.
The specific heat capacity of lead is 128 J/kg∘C128\text{ J/kg}^\circ\text{C}128 J/kg∘C. Calculate the energy needed to raise the temperature of the lead to its melting point of 327∘C327^\circ\text{C}327∘C.
The specific latent heat of fusion of lead is 22 400 J/kg22\,400\text{ J/kg}22400 J/kg. Calculate the energy needed to melt all of the lead at 327∘C327^\circ\text{C}327∘C.
Use your answers from (a)(i) and (a)(ii) to calculate the total energy needed to heat and melt 1.5 kg of lead from 27∘C27^\circ\text{C}27∘C into liquid at 327∘C327^\circ\text{C}327∘C. Write your answer in standard form and to 2 significant figures.
Suggest two reasons why the actual electrical energy needed from a heating element in a real laboratory experiment would be more than the calculated value in (a)(iii).
Suggest one advantage of repeating an experiment three times and calculating a mean.