Question

取1mol NaOH放入160克水中完全溶解，所得溶液的溶質(zhì)質(zhì)量分?jǐn)?shù)是多少？取此溶液跟500克某未知濃度的鹽酸恰好完全反應(yīng)，求該稀鹽酸中溶質(zhì)的質(zhì)量分?jǐn)?shù)是多少？

Answer 1

考點(diǎn)：根據(jù)化學(xué)反應(yīng)方程式的計(jì)算,有關(guān)溶質(zhì)質(zhì)量分?jǐn)?shù)的簡(jiǎn)單計(jì)算

專(zhuān)題：溶質(zhì)質(zhì)量分?jǐn)?shù)與化學(xué)方程式相結(jié)合的計(jì)算

分析：根據(jù)溶質(zhì)質(zhì)量分?jǐn)?shù)公式計(jì)算所得溶液的溶質(zhì)質(zhì)量分?jǐn)?shù)，依據(jù)化學(xué)方程式的有關(guān)計(jì)算利用氫氧化鈉的質(zhì)量求算鹽酸的質(zhì)量．

解答：解：1mol NaOH的質(zhì)量為：1mol×40g/mol=40g，故所得溶液的溶質(zhì)質(zhì)量分?jǐn)?shù)是

40g

40g+160g

×100%=20%，
設(shè)該稀鹽酸中溶質(zhì)的質(zhì)量分?jǐn)?shù)為x
NaOH+HCl=NaCl+H₂O
40   36.5
40g  500g×x

40

36.5

=

40g

500g×x

  x=7.3%
答：所得溶液的溶質(zhì)質(zhì)量分?jǐn)?shù)是20%，該稀鹽酸中溶質(zhì)的質(zhì)量分?jǐn)?shù)是7.3%．

點(diǎn)評(píng)：加強(qiáng)對(duì)溶質(zhì)質(zhì)量分?jǐn)?shù)公式的掌握以及根據(jù)化學(xué)方程式的計(jì)算的掌握是正確解答本題的關(guān)鍵．