Question

t℃時(shí)，4.8 g鎂與一定量的稀鹽酸恰好完全反應(yīng)，反應(yīng)后得飽和溶液，其溶質(zhì)質(zhì)量分?jǐn)?shù)為25%。求所用鹽酸中氯化氫的質(zhì)量分?jǐn)?shù)。

Answer 1

解：設(shè)鹽酸中氯化氫的質(zhì)量為x，生成氯化鎂和氫氣的質(zhì)量分別為y和z。

Mg+2HCl===MgCl₂+H₂↑                                         (1分)

24   73     95     2

4.8 g  x      y     z

24/73=4.8 g/x    x=14.6 g                                           (1分)

24/95=4.8 g/y       y=19 g                                          (1分)

24/2=4.8 g/z        z=0.4 g                                         (1分)

氯化鎂溶液的質(zhì)量：19 g/25%=76 g                                 (1分)

鹽酸溶液的質(zhì)量：76 g+0.4 g－4.8 g=71.6 g                            (1分)

鹽酸溶液中氯化氫的質(zhì)量分?jǐn)?shù)：×100%=20.4%                 (1分)

答：鹽酸溶液中氯化氫的質(zhì)量分?jǐn)?shù)是20.4%。                         (1分)