Question

17．將100g 10%的氯化鈉溶液分成兩等分．
（1）向其中一份中加入10g水，請(qǐng)計(jì)算所得溶液中溶質(zhì)的質(zhì)量分?jǐn)?shù)（精確到0.1%）；
（2）向另一份中溶解10g氯化鈉，請(qǐng)計(jì)算所得溶液中溶質(zhì)的質(zhì)量分?jǐn)?shù)．

Answer 1

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

解答 解：將100g10%的氯化鈉溶液分成兩等分，每份溶液的質(zhì)量為50g；由于溶液具有均一性，每份溶液的溶質(zhì)質(zhì)量分?jǐn)?shù)均為10%．
（1）向其中一份中加入10g水，請(qǐng)計(jì)算所得溶液中溶質(zhì)的質(zhì)量分?jǐn)?shù)為$\frac{50g×10%}{50g+10g}×$100%≈8.3%．
（2）向另一份中溶解10g氯化鈉，所得溶液中溶質(zhì)的質(zhì)量分?jǐn)?shù)為$\frac{50g×10%+10g}{50g+10g}$×100%=25%．
答：（1）所得溶液中溶質(zhì)的質(zhì)量分為8.3%；（2）所得溶液中溶質(zhì)的質(zhì)量分?jǐn)?shù)為25%．

點(diǎn)評(píng) 本題難度不大，掌握溶質(zhì)的質(zhì)量分?jǐn)?shù)=$\frac{溶質(zhì)質(zhì)量}{溶液質(zhì)量}×$100%、溶質(zhì)質(zhì)量=溶液質(zhì)量×溶質(zhì)的質(zhì)量分?jǐn)?shù)是正確解答本題的關(guān)鍵．