A solution containing $2.5\times {10}^{-3} \mathrm{kg}$ of a solute dissolved in $75\times {10}^{-3} \mathrm{kg}$ of water boils at $373.535 K$ . The molar mass of the solute is ______ g mol^-1. [nearest integer] (Given: ${\mathrm{K}}_{\mathrm{b}}\left({\mathrm{H}}_2\mathrm{O}\right)=0.52 K \mathrm{Kg}$ ${\mathrm{mol}}^{-1}$, boiling point of water =373.15 K )