解：設(shè)該氫氧化鈉溶液的溶質(zhì)質(zhì)量分?jǐn)?shù)為?$x。$?
?$\mathrm {CuCl}_2+2 \mathrm {NaOH}\xlongequal[ ]{ }2 \mathrm {NaCl}+\mathrm {Cu}(\mathrm {OH)}_2↓$?
80 98
50g×?$x$ ? 9.8g
?$\frac {80 }{98 }=\frac {50\mathrm {g}×x }{9.8\mathrm {g} }，$?解得?$x= 16\%$?
答：氫氧化鈉溶液的溶質(zhì)質(zhì)量分?jǐn)?shù)為?$16\%。$?
