Question

100g某硫酸恰好與13g鋅完全起反應(yīng)．試計(jì)算：
①這種硫酸中溶質(zhì)的質(zhì)量分?jǐn)?shù)．
②所得溶液溶質(zhì)質(zhì)量分?jǐn)?shù)．

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)的簡單計(jì)算

專題：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)鋅與硫酸反應(yīng)的化學(xué)方程式，由13g鋅的質(zhì)量計(jì)算恰好完全反應(yīng)時放出氫氣的質(zhì)量、參加反應(yīng)的硫酸的質(zhì)量、及反應(yīng)生成硫酸鋅的質(zhì)量，然后分別利用溶液中溶質(zhì)質(zhì)量分?jǐn)?shù)的計(jì)算公式，求出硫酸溶液中溶質(zhì)的質(zhì)量分?jǐn)?shù)和反應(yīng)后所得溶液中溶質(zhì)的質(zhì)量分?jǐn)?shù)．

解答：解：設(shè)硫酸溶液中溶質(zhì)的質(zhì)量為x，生成硫酸鋅的質(zhì)量為y，生成氫氣的質(zhì)量為z
Zn+H₂SO₄=ZnSO₄+H₂↑
65　98   161   2
13g  x    y    z

65

13g

=

98

x

=

161

y

=

2

z

x=19.6g
y=32.2g
z=0.4g
硫酸溶液中溶質(zhì)的質(zhì)量分?jǐn)?shù)=

19.6g

100g

×100%=l9.6%
硫酸鋅溶液的溶質(zhì)質(zhì)量分?jǐn)?shù)=

32.2g

13g+100g-0.4g

×100%=28.6%
答：
①硫酸溶液中溶質(zhì)的質(zhì)量分?jǐn)?shù)為19.6%；
②反應(yīng)后所得溶液中溶質(zhì)的質(zhì)量分?jǐn)?shù)為28.6%．

點(diǎn)評：根據(jù)質(zhì)量守恒定律，反應(yīng)后所得溶液的質(zhì)量=參加反應(yīng)金屬的質(zhì)量+加入的稀硫酸的質(zhì)量-放出氣體的質(zhì)量．