解：設(shè)稀鹽酸中溶質(zhì)的質(zhì)量為?$x。$??$ $?
?$\mathrm {CaCO}_3+2\mathrm {HCl}\xlongequal[ ]{ }\mathrm {CaCl}_2+\mathrm {H}_2\mathrm {O}+\mathrm {CO}_2↑$?
73 44
?$x$? 4.4 g
?$\frac {73}{44}=\frac {x}{4.4 \mathrm {g}}，$?解得?$ x=7.3 \mathrm {g} $
?
?$\frac {7.3 \mathrm {g}}{73 \mathrm {g}}×100\%=10\% $
?
答：稀鹽酸的溶質(zhì)質(zhì)量分?jǐn)?shù)是?$10\%。$?
