Question

醫(yī)療上常用溶質(zhì)的質(zhì)量分?jǐn)?shù)約為0.9%的生理鹽水給病人補(bǔ)充體液，現(xiàn)用45g溶質(zhì)質(zhì)量分?jǐn)?shù)為10%的氯化鈉溶液來配制這種生理鹽水，需加水的質(zhì)量約為（ ）
A．405g
B．450g
C．455g
D．500g

Answer 1

【答案】分析：根據(jù)加水稀釋前后溶液中溶質(zhì)質(zhì)量不變，計(jì)算加入的水的質(zhì)量．已知溶質(zhì)的質(zhì)量=溶質(zhì)質(zhì)量分?jǐn)?shù)×溶液的質(zhì)量．
解答：解：根據(jù)加水前后溶質(zhì)的質(zhì)量不變列等式，設(shè)需要加水的質(zhì)量為x
45g×10%=（45g+x）×0.9%
解之得 x=455g
故選C
點(diǎn)評(píng)：本題為應(yīng)用溶液的溶質(zhì)質(zhì)量分?jǐn)?shù)計(jì)算溶液中溶質(zhì)質(zhì)量和溶劑質(zhì)量的基本計(jì)算，掌握溶液加水稀釋時(shí)溶質(zhì)的質(zhì)量不變，計(jì)算時(shí)注意計(jì)算結(jié)果的準(zhǔn)確性．