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A Level Specific Heat Capacity Questions

Q12. (a) Lead has a specific heat capacity of 130 J kg–1 K–1. Explain what is meant by this statement.

It takes 130 J of energy to raise the temperature of a mass of 1 kg of lead by 1 K , without changing its state.

[1 mark]

(b) Lead of mass 0.75 kg is heated from 21 ºC to its melting point and continues to be heated until it has all melted.

Calculate how much energy is supplied to the lead. Give your answer to an appropriate number of significant figures.

melting point of lead = 327.5 ºC
specific latent heat of fusion of lead = 23 000 J kg–1

There are two things that the supplied energy has to do - it has to raise the temperature of the lead to melting point and then melt the lead.

Q = mcΔT + ml

Q = 0.75 x 130 x (327.5 – 21) + 0.75 x 23000

Q = 29884 + 17250

Q = 47134

Q = 4.7 x 104 J - answer to 2 sf - although some values were given to more sf, some were only to 2sf, therefore the answer must be given to 2sf.

 

[3 marks]

(Total 4 marks)