Question

Identify the process in the given reactions:

$$\begin{gathered} 1.\begin{array}{l}ZnC{O}_3\stackrel{\mathrm{\Delta }}{\to }ZnO+C{O}_2\end{array} \\ 2.\begin{array}{l}ZnS+O_2\stackrel{\mathrm{\Delta }}{\to }ZnO+S{O}_2\end{array} \end{gathered}$$

• A. A = roasting; B = calcination.
• B. A = calcination; B = roasting
• C. A = B = roasting
• D. A = B = calcination

Answer 1

The correct option is B

A = calcination; B = roasting

Explanation for the correct option:

Calcination:

1. In the calcination process, the ore is converted into oxide ore in a limited supply of air.
2. This process is mostly used for carbonates, bicarbonates and hydroxides.

Roasting:

1. In the roasting process, the ore is converted into its oxide ore by heating it in the presence of excess air.
2. This process is mostly used for Sulphide ores.

In reaction 1,

1. Carbonate ore of $\mathrm{Zn}$ is heated in the absence of oxygen.
2. In this reaction, ore of $\mathrm{Zn}$ is converted into oxide ore ($\mathrm{ZnO}$) and Carbon dioxide gas is formed in this reaction.
3. So, this process is called calcination.

In reaction 2,

1. 2 moles of $\mathrm{ZnS}$ react with 3 moles of O₂ to form 2 moles of $\mathrm{ZnO}$ and 2 moles of ${\mathrm{SO}}_2$.
2. The sulphide ore of $\mathrm{Zn}$ in the presence of oxygen is converted into its oxide ore ($\mathrm{ZnO}$).
3. So, this process is called roasting.

Final Answer: Hence, the correct option is (B).