Outline the process of extracting zinc from its ore, including the balanced chemical equations for roasting and reduction.

$$2\text{ZnS(s)} + 3\text{O}_2\text{(g)} \rightarrow 2\text{ZnO(s)} + 2\text{SO}_2\text{(g)}$$

The equation for the reaction is:

$$\boxed{2\text{ZnS(s)} + 3\text{O}_2\text{(g)} \rightarrow 2\text{ZnO(s)} + 2\text{SO}_2\text{(g)}}$$

b)
The by-product of the roasting process is sulfur dioxide ($\text{SO}_2$).

• Sulfur dioxide is a major air pollutant that causes acid rain when it dissolves in atmospheric water, damaging buildings, forests, and aquatic ecosystems.
• It is also a respiratory irritant, contributing to breathing problems and respiratory diseases in humans and animals.

c) (i)
The reducing agent used in the furnace during the extraction of zinc by the reduction method is carbon (coke).

c) (ii)

$$\text{ZnO(s)} + \text{CO(g)} \rightarrow \text{Zn(g)} + \text{CO}_2\text{(g)}$$

The equations for the reduction processes are:

$$\boxed{\begin{align*} \text{ZnO(s)} + \text{C(s)} &\rightarrow \text{Zn(g)} + \text{CO(g)} \\ \text{ZnO(s)} + \text{CO(g)} &\rightarrow \text{Zn(g)} + \text{CO}_2\text{(g)} \end{align*}}$$

d)
The electrolyte used in the electrolytic method for zinc extraction is aqueous zinc sulfate ($\text{ZnSO}_4\text{(aq)}$).
It is acquired by dissolving the zinc oxide ($\text{ZnO}$) obtained from the roasting process in dilute sulfuric acid ($\text{H}_2\text{SO}_4$).

$$\text{ZnO(s)} + \text{H}_2\text{SO}_4\text{(aq)} \rightarrow \text{ZnSO}_4\text{(aq)} + \text{H}_2\text{O(l)}$$