Question

Which of the following reactions are examples of roasting?

• A. ${\text{CaCO}}_3\text{(s)}$ $\to$ $\text{CaO (s)}+{\text{CO}}_2\text{(g)}$
• B. $4{\text{FeS}}_2\text{(s)}$ + ${\text{11O}}_2\text{(g)}$ $\to$ $2{\text{Fe}}_2{\text{O}}_3\text{(s)}$ + $8{\text{SO}}_2\text{(g)}$
• C. $2{\text{Al(OH)}}_3\text{(s)}$ $\to$ ${\text{Al}}_2{\text{O}}_3\text{(s)}$ + ${\text{3H}}_2\text{O (l)}$
• D. $2\text{CuS(s)}$+ $2{\text{O}}_2\text{(g)}$ $\to$ $2\text{Cu(s)}$ + ${\text{2SO}}_2\text{(g)}$

Answer 1

Answer: (B), (D)

The correct options are
B $4{\text{FeS}}_2\text{(s)}$ + ${\text{11O}}_2\text{(g)}$ $\to$ $2{\text{Fe}}_2{\text{O}}_3\text{(s)}$ + $8{\text{SO}}_2\text{(g)}$
D $2\text{CuS(s)}$+ $2{\text{O}}_2\text{(g)}$ $\to$ $2\text{Cu(s)}$ + ${\text{2SO}}_2\text{(g)}$

Roasting is a process in which an ore is heated in the presence of oxygen to convert it into metal oxide. Roasting is generally used for sulphide ores. For example:
$4{\text{FeS}}_2\text{(s)}$ + ${\text{11O}}_2\text{(g)}$ $\to$ $2{\text{Fe}}_2{\text{O}}_3\text{(s)}$ + $8{\text{SO}}_2\text{(g)}$
$2\text{CuS(s)}$+ $2{\text{O}}_2\text{(g)}$ $\to$ $2\text{Cu(s)}$ + ${\text{2SO}}_2\text{(g)}$