Calculate the mass percent $(m/m)$of a solution containing $15.5\mathrm{g}\text{of}{\mathrm{Na}}_2{\mathrm{SO}}_4\text{and}75.5\mathrm{g}\text{of}{\mathrm{H}}_2\mathrm{O}.\left(9.4\right)$localid="1654600997108" $75.5gof{H}_{2}O.(9.4)$

The quantity of an element or compound or a constituent in a mixture can be expressed in mass percentage.

Solution is $15.5\mathrm{g}\text{of}{\mathrm{Na}}_2{\mathrm{SO}}_4\text{and}75.5\mathrm{g}\text{of}{\mathrm{H}}_2\mathrm{O}.\left(9.4\right)$Want mass percent (%m/m) of localid="1654601014837" $N{a}_{2}S{O}_4$

In the definition of mass percent, the mass in grammes of the solute and solution is used to determine the mass percent.

Factors of conversion/equalities,

localid="1654601020438" $Masspercent(\%m/m)=\frac{Massofsolute}{massofsolute+massofsolvent}\times 100$

localid="1654601025749" $Masspercent(\%m/m)=\frac{gramsofsolute}{gramsofsolution}\times 100$

The weight of the solute as well as the solution are calculated using the data.

$massofsolute=15.5gN{a}_{2}S{O}_4$

$\frac{massofsolvent=+75.5g{H}_{2}O}{massofsolution=91.0gsolution}$

$\text{Mass percent}(\mathrm{\%}\mathrm{m}/\mathrm{m})=\frac{15.5g\mathrm{Na}{\mathrm{Na}}_4}{91.0\mathrm{g}\text{solution}}\times 100$

$=17.0\%(m/m)$