One litre $2M{Na}_3{PO}_4$ and 1 litre of $1M{BaCl}_2$ solutions are mixed. What is the normality of phosphate ions in the filtrate ?

$2{Na}_3{PO}_4+{3BaCl}_2⟶{Ba}_3(P{O}_4{)}_2+6NaCl$

Equivalents of ${Na}_3{PO}_4=1\times 2\times 3$

$\mathrm{Equivalents} \mathrm{of} {\mathrm{BaCl}}_2=1\times 1\times 2$

$\therefore Equivalents of P{O}_4^{-3}ppted=2$

Equivalents in filtrate = 6 – 2 = 4

Normality of $P{O}_4^{-3}=\frac{4}{1+1}=2$

Therefore, the normality of phosphate ions in the filtrate is 2.