91Ó°ÊÓ

Solution concentration as percent by mass is calculated as

\({\rm{\% mass = }}\frac{{{\rm{mass solute}}}}{{{\rm{mass solution}}}}{\rm{ \times 100\% }}\)

Solution density is the ratio of the mass of solution and the volume of the solution that can be calculated as

\({\rm{Solution}}\,\,\,{\rm{density = }}\frac{{{\rm{mass of}}\,{\rm{solution}}}}{{{\rm{Volume}}\,{\rm{of solution}}}}\)

Given

Volume of solution = 45.0 mL

% mass HCl =37.21 %

Volume of solution = 1.00 L

\(\begin{align}{\rm{mass of}}\,{\rm{solution}} &= {\rm{Solution}}\,\,\,{\rm{density}} \times {\rm{Volume}}\,{\rm{of solution}}\\ &= 1.19\frac{{\rm{g}}}{{{\rm{mL}}}} \times 45\,{\rm{mL}}\\ &= \,53.55\,{\rm{g}}\end{align}\)

\(\begin{align}{\rm{mass of}}\,{\rm{HCl}} = \,0.3721 \times 53.55\,{\rm{g}}\\{\rm{ = 19}}{\rm{.9g}}\end{align}\)

A 45.0 mL of 37.21 % HCl solution contains 19.9 g HCl.