The minimum volume of water required to dissolve $2.78 \mathrm{g}$ lead $\left(\mathrm{II}\right)$ chloride to get a saturated solution$({\mathrm{K}}_{\mathrm{sp}}\hspace{0.17em}\mathrm{of}\hspace{0.17em}{\mathrm{PbCl}}_{\mathrm{2}}=3.2\times {10}^{-8}$

molar mass of ${\mathrm{PbCl}}_2=278 \mathrm{g} {\mathrm{mol}}^{-1}$ ) is______ L.