Question

Which of the following reaction does not represent a roasting method?

• A. $2ZnS\left(s\right)+3O_2\stackrel{\Delta }{\to }2ZnO\left(s\right)+2S{O}_2\left(g\right)$
• B. $2PbS\left(s\right)+3O_2\stackrel{\Delta }{\to }2PbO\left(s\right)+2S{O}_2\left(g\right)$
• C. $2C{u}_{2}S\left(s\right)+3O_2\stackrel{\Delta }{\to }2C{u}_{2}O\left(s\right)+2S{O}_2\left(g\right)$
• D. None of the above

Answer 1

The correct option is D None of the above

In isolation of metal, conversion of ore to oxide is the first step. It can be done by calcination or roasting method.
In roasting, the concentrated ore is heated at high temperature below the melting point of the metal in excess of air. This reaction occurs in reverberatory furnace.
Generally, metal sulphides are easily converted to metal oxides by roasting.
Example:
$2ZnS\left(s\right)+3O_2\stackrel{\Delta }{\to }2ZnO\left(s\right)+2S{O}_2\left(g\right)$
$2PbS\left(s\right)+3O_2\stackrel{\Delta }{\to }2PbO\left(s\right)+2S{O}_2\left(g\right)$
$2C{u}_{2}S\left(s\right)+3O_2\stackrel{\Delta }{\to }2C{u}_{2}O\left(s\right)+2S{O}_2\left(g\right)$

Thus, all the given reactions define roasting method.
Hence, option (d) is correct.