Question

18．在90g10%的氯化鈉溶液中再加入10g氯化鈉完全溶解后的溶質(zhì)質(zhì)量分?jǐn)?shù)為19%或加入10g水后溶質(zhì)質(zhì)量分?jǐn)?shù)為9%．

Answer 1

分析 根據(jù)題意，結(jié)合溶質(zhì)質(zhì)量分?jǐn)?shù)=$\frac{溶質(zhì)質(zhì)量}{溶液質(zhì)量}$×100%，進(jìn)行分析解答即可．

解答 解：在90g10%的氯化鈉溶液中加入10g水，則所得溶液中溶質(zhì)的質(zhì)量分?jǐn)?shù)為$\frac{90g×10%}{90g+10g}×$100%=9%．
在90g10%的氯化鈉溶液中加入10g氯化鈉，則所得溶液中溶質(zhì)的質(zhì)量分?jǐn)?shù)為$\frac{90g×10%+10g}{90g+10g}×$100%=19%．
答：兩種溶液中溶質(zhì)的質(zhì)量分?jǐn)?shù)分別是19%、9%．

點(diǎn)評 本題難度不大，靈活運(yùn)用溶質(zhì)質(zhì)量分?jǐn)?shù)的計算公式是正確解答此類題的關(guān)鍵．