Question

Group V cations are precipitated in form of carbonates by $(N{H}_4{)}_{2}C{O}_3$. Why can we not use $N{a}_{2}C{O}_3$ in stead of $(N{H}_4{)}_{2}C{O}_3$?

• A. Because $N{a}_{2}C{O}_3$ will precipitate $MgC{O}_3$
• B. Because $N{a}_{2}C{O}_3$ is insoluble in water
• C. Because it is an ionic compound
• D. None of these

Answer 1

The correct option is A Because $N{a}_{2}C{O}_3$ will precipitate $MgC{O}_3$

Group V cations are precipitated in form of carbonates by $(N{H}_4{)}_{2}C{O}_3$. We can not use $N{a}_{2}C{O}_3$ in stead of $(N{H}_4{)}_{2}C{O}_3$ because $N{a}_{2}C{O}_3$ will precipitate $MgC{O}_3$
The solubility product of $MgC{O}_3$ is high and when we use $N{a}_{2}C{O}_3$, it will completely ionize and supply high concentration of carbonate ions,
the ionic product of $MgC{O}_3$ will exceed solubility product and cause precipitation.