Question

When white phosphorus is boiled with alkali in an inert atmosphere and forms product ‘A’.When $1\mathrm{mol}$ A with an excess of ${\mathrm{AgNO}}_3$ in aqueous medium gives _______mol(s) of $\mathrm{Ag}$(Round to the nearest integer).

Answer 1

Step1:

• When white phosphorus reacts with hydroxide ions.
• $$\begin{gathered} {\mathrm{P}}_4\left(\mathrm{s}\right)+3{\mathrm{OH}}^{-}\left(\mathrm{l}\right)+3{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to {\mathrm{PH}}_3\left(\mathrm{g}\right)+3{\mathrm{H}}_2{\mathrm{PO}}_2\left(\mathrm{l}\right) \\ \left(\mathrm{A}\right) \end{gathered}$$

Step 2:

• $1\mathrm{mol}$of A reacts with ${\mathrm{AgNO}}_3$.
• $$\begin{gathered} {\mathrm{H}}_2{{\mathrm{PO}}_2}^{-}\left(\mathrm{l}\right)+4{\mathrm{Ag}}^{+}\left(\mathrm{s}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)\to 4\mathrm{Ag}\left(\mathrm{s}\right)+{\mathrm{H}}_3{\mathrm{PO}}_4\left(\mathrm{l}\right)+3{\mathrm{H}}^{+}\left(\mathrm{g}\right) \\ 4\mathrm{mol} \end{gathered}$$

Therefore, when $1\mathrm{mol}$ ${\mathrm{H}}_2{\mathrm{PO}}_2$ with an excess of ${\mathrm{AgNO}}_3$ in an aqueous medium gives $4\mathrm{moles}$ of $\mathrm{Ag}$.