Physics 5054 · O Level · Melting, boiling and evaporation
Melting, boiling and evaporation — practice question
Old gold jewellery is heated in a furnace until it melts. Fig. 3.1 shows the molten gold being poured into a mould so that a gold bar is formed.
The melting point of gold is $1100\,^{\circ}\text{C}$.
(a)[2]
State two differences between the molecular structure of gold at $1200\,^{\circ}\text{C}$ and its structure at $1000\,^{\circ}\text{C}$.
(b(i))[2]
Explain, in terms of the molecules, why thermal energy must be supplied to melt the gold.
(b(ii))[2]
The specific latent heat of fusion of gold is $64\,\text{kJ kg}^{-1}$. Calculate the thermal energy needed to melt all the gold.
Worked solution & mark scheme
This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Molecules arranged irregularly” …