A solution of $N{a}_{3}P{O}_4$ is added dropwise to a solution that is $0\mathrm{.}0388M_{?}$ in $A{g}^{+}$and $0\mathrm{.}00393M_{?}$ in $C{u}^{2+}.$

The $K_{5p}$ of $A{g}_{3}P{O}_4$ is $8\mathrm{.}89e-17.$

The $K_{5p}$ of $C{u}_3(P{O}_4{)}_2$ is $1\mathrm{.}4e-37.$

$($a$)$ What concentration of $P{O}_4^{3-}$ is necessary to begin precipitation? $($Neglect volume changes.$)$

$[P{O}_4^{3-}]=$

M$.$

$($b$)$ Which cation precipitates first?

$A{g}^{+}$

$C{u}^{2+}$

$($c$)$ What is the concentration of $P{O}_4^{3-}$ when the second cation begins to precipitate?

$[P{O}_4^{3-}]=$

M$.$