Question

質(zhì)量分?jǐn)?shù)為10%的食鹽溶液100g加入10g食鹽固體，把溶液中的水蒸發(fā)掉一半，溶質(zhì)的質(zhì)量分?jǐn)?shù)為多少？（此時(shí)假設(shè)仍不飽和）

Answer 1

考點(diǎn)：有關(guān)溶質(zhì)質(zhì)量分?jǐn)?shù)的簡(jiǎn)單計(jì)算

專題：溶液的組成及溶質(zhì)質(zhì)量分?jǐn)?shù)的計(jì)算

分析：根據(jù)溶質(zhì)質(zhì)量=溶液質(zhì)量×溶質(zhì)的質(zhì)量分?jǐn)?shù)，溶劑質(zhì)量=溶液質(zhì)量-溶質(zhì)質(zhì)量，結(jié)合溶質(zhì)質(zhì)量分?jǐn)?shù)=

溶質(zhì)質(zhì)量

溶液質(zhì)量

×100%，進(jìn)行分析解答．

解答：解：質(zhì)量分?jǐn)?shù)為10%的食鹽溶液100g中含有氯化鈉的質(zhì)量為100g×10%=10g，含有水的質(zhì)量為100g-10g=90g，其質(zhì)量的一半是90g÷2=45g；加入10g食鹽固體，把溶液中的水蒸發(fā)掉一半，溶質(zhì)的質(zhì)量分?jǐn)?shù)為

10g+10g

100g+10g-45g

×100%≈30.8%．
答：溶質(zhì)的質(zhì)量分?jǐn)?shù)為30.8%．

點(diǎn)評(píng)：本題難度不大，掌握溶質(zhì)質(zhì)量=溶液質(zhì)量×溶質(zhì)的質(zhì)量分?jǐn)?shù)、溶劑質(zhì)量=溶液質(zhì)量-溶質(zhì)質(zhì)量、溶質(zhì)質(zhì)量分?jǐn)?shù)=

溶質(zhì)質(zhì)量

溶液質(zhì)量

×100%是正確解答本題的關(guān)鍵．