Question

將5克鋅投入到105克稀硫酸里，鋅全部溶解生成硫酸鋅，反應(yīng)后硫酸鋅溶液的溶質(zhì)質(zhì)量分數(shù)為C₁；10克鋅投入100克稀硫酸時里，鋅也全部反應(yīng)為硫酸鋅，反應(yīng)后硫酸鋅溶液的溶質(zhì)質(zhì)量分數(shù)為C₂．則C₁和C₂的大小關(guān)系是（ ）

• A．C₁=C₂
• B．C₂＜2C₁
• C．C₂＞2C₁
• D．C₂=2C₁

Answer 1

【答案】分析：10g鋅全部反應(yīng)為硫酸鋅的質(zhì)量為5g鋅全部溶解生成硫酸鋅質(zhì)量的2倍，即溶液的溶質(zhì)質(zhì)量分數(shù)為C₂的硫酸鋅溶液中溶質(zhì)質(zhì)量是溶液的溶質(zhì)質(zhì)量分數(shù)為C₁的硫酸鋅溶液中溶質(zhì)質(zhì)量的2倍；若的反應(yīng)不放出氫氣，反應(yīng)后兩溶液的質(zhì)量相等，此時C₂=2C₁；考慮到10g鋅全部反應(yīng)放出氫氣質(zhì)量大于10g鋅全部反應(yīng)放出氫氣質(zhì)量，即溶液的溶質(zhì)質(zhì)量分數(shù)為C₂的硫酸鋅溶液中溶液質(zhì)量小于溶液的溶質(zhì)質(zhì)量分數(shù)為C₁的硫酸鋅溶液中溶液質(zhì)量，因此，C₂＞2C₁．
解答：解：根據(jù)鋅與硫酸反應(yīng)生成硫酸鋅和氫氣，5g鋅全部反應(yīng)生成硫酸鋅及放出氫氣的質(zhì)量均為10g鋅全部反應(yīng)生成硫酸鋅質(zhì)量及放出氫氣質(zhì)量的一半；
根據(jù)質(zhì)量守恒定律，溶液的溶質(zhì)質(zhì)量分數(shù)為C₂的硫酸鋅溶液中溶液質(zhì)量小于溶液的溶質(zhì)質(zhì)量分數(shù)為C₁的硫酸鋅溶液中溶液質(zhì)量，而溶液的溶質(zhì)質(zhì)量分數(shù)為C₂的硫酸鋅溶液中溶質(zhì)質(zhì)量是溶液的溶質(zhì)質(zhì)量分數(shù)為C₁的硫酸鋅溶液中溶質(zhì)質(zhì)量的2倍；
根據(jù)溶液中溶質(zhì)質(zhì)量分數(shù)=×100%，可判斷得到C₁和C₂的大小關(guān)系為C₂＞2C₁；
故選C．
點評：根據(jù)質(zhì)量守恒定律，鋅與硫酸反應(yīng)后所得溶液的質(zhì)量=鋅的質(zhì)量+所加稀硫酸的質(zhì)量-放出氫氣的質(zhì)量．