Unwanted gold jewellery is heated in a furnace until it melts. Fig. 3.1 shows the liquid gold being poured into a mould to make a gold bar. [Figure 3.1] The melting point of gold is 1100°C.

1. (a)State two ways in which the molecular structure of gold at 1200 °C differs from its structure at 1000 °C. 1. 2.[2]
2. (b)(i)In the furnace, 0.84 kg of solid gold reaches its melting point. The furnace continues to supply thermal energy and, after a short time, all the gold melts. Explain, in terms of the molecules, why thermal energy is needed to melt the gold.[2]
3. (b)(ii)The specific latent heat of fusion of gold is 64 kJ/kg. Calculate the thermal energy supplied to melt all the gold. thermal energy = [2]

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