# Consider two chemical reactions (A) and (B) that take

Question:

Consider two chemical reactions (A) and (B) that take place during metallurgical process :

(A) $\mathrm{ZnCO}_{3(\mathrm{~s})} \stackrel{\Delta}{\longrightarrow} \mathrm{ZnO}_{(\mathrm{s})}+\mathrm{CO}_{2(\mathrm{~g})}$

(B) $2 \mathrm{ZnS}_{(\mathrm{s})}+3 \mathrm{O}_{2(\mathrm{~g})} \stackrel{\Delta}{\longrightarrow} 2 \mathrm{ZnO}_{(\mathrm{s})}+2 \mathrm{SO}_{2(\mathrm{~g})}$

1. (A) is calcination and (B) is roasting

2.  Both (A) and (B) are producing same product so both are roasting

3. Both (A) and (B) are producing same product so both are calcination

4. (A) is roasting and (B) is calcination

Correct Option: 1

Solution:

(A) $\mathrm{ZnCO}_{3}$ (S) $\stackrel{\Delta}{\longrightarrow} \mathrm{ZnO}$ (s) $+\mathrm{CO}_{2}$ (g)

Heating in absence of oxygen in calcination.

(B) $2 \mathrm{Zns}(\mathrm{s})+3 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow 2 \mathrm{ZnO}(\mathrm{g})+2 \mathrm{SO}_{2}(\mathrm{~g})$

heating in presence of oxygen in roasting

Hence (A) is calcination while (B) in roasting.