Question

17．向100g硝酸銀溶液中加入稀鹽酸恰好完全反應(yīng)，過濾后所得溶液的質(zhì)量等于原硝酸銀溶液的質(zhì)量，則所加稀鹽酸中溶質(zhì)的質(zhì)量分?jǐn)?shù)為（　�。�

• A． 42.1%
• B． 43.5%
• C． 56.9%
• D． 25.4%

Answer 1

分析 根據(jù)氯化氫和硝酸銀生成氯化銀沉淀和硝酸，根據(jù)質(zhì)量守恒定律可知，鹽酸溶液的質(zhì)量和硝酸銀溶液的質(zhì)量之和等于氯化銀沉淀質(zhì)量和硝酸溶液的質(zhì)量之和，則濾液的質(zhì)量等于鹽酸溶液的質(zhì)量+硝酸銀溶液的質(zhì)量-氯化銀沉淀的質(zhì)量．又因?yàn)闉V液的質(zhì)量等于所加硝酸銀溶液的質(zhì)量，所以鹽酸的質(zhì)量=沉淀的質(zhì)量進(jìn)行分析．

解答 解：氯化氫和硝酸銀生成氯化銀沉淀和硝酸，根據(jù)質(zhì)量守恒定律可知，鹽酸溶液的質(zhì)量和硝酸銀溶液的質(zhì)量之和等于氯化銀沉淀質(zhì)量和硝酸溶液的質(zhì)量之和，則濾液的質(zhì)量等于鹽酸溶液的質(zhì)量+硝酸銀溶液的質(zhì)量-氯化銀沉淀的質(zhì)量．又因?yàn)闉V液的質(zhì)量等于所加硝酸銀溶液的質(zhì)量，所以鹽酸的質(zhì)量=沉淀的質(zhì)量．設(shè)氯化氫的質(zhì)量是X，氯化銀的質(zhì)量是Y，則鹽酸的質(zhì)量等于沉淀的質(zhì)量．
AgNO₃+HCl═AgCl↓+HNO₃
     36.5   143.5
     X        Y
$\frac{36.5}{X}$=$\frac{143.5}{Y}$
Y=$\frac{143.5X}{36.5}$
鹽酸的質(zhì)量是$\frac{143.5X}{36.5}$
鹽酸溶液中溶質(zhì)的質(zhì)量分?jǐn)?shù)=$\frac{X}{\frac{143.5X}{36.5}}$×100%═25.4%．
故選：D．

點(diǎn)評(píng) 本題的關(guān)鍵是得到鹽酸的質(zhì)量等于沉淀的質(zhì)量，就本題來說，可以假定鹽酸的質(zhì)量是36.5克，則沉淀的質(zhì)量是143.5克，從而計(jì)算出鹽酸的溶質(zhì)的質(zhì)量分?jǐn)?shù)，這是最簡單的方法．