Question

將60℃時(shí)的100g某物質(zhì)的溶液降溫至30℃，有17g該物質(zhì)的無(wú)水晶體析出，此時(shí)溶液中溶質(zhì)的質(zhì)量分?jǐn)?shù)為20%．求60℃時(shí)的原溶液的溶質(zhì)質(zhì)量分?jǐn)?shù)．

Answer 1

【答案】分析：將60℃時(shí)的100g某物質(zhì)的溶液降溫至30℃，有17g該物質(zhì)的無(wú)水晶體析出，此時(shí)溶液的質(zhì)量是83g（100g-17g=83g），根據(jù)此時(shí)溶液的質(zhì)量乘以此時(shí)溶質(zhì)質(zhì)量分?jǐn)?shù)便可得到30℃時(shí)溶液中溶質(zhì)的質(zhì)量，用析出溶質(zhì)的質(zhì)量加上30℃時(shí)溶液中溶質(zhì)的質(zhì)量就是60℃時(shí)的原溶液中溶質(zhì)的質(zhì)量，最后根據(jù)質(zhì)量分?jǐn)?shù)公式計(jì)算即可．
解答：解：根據(jù)溶液中溶質(zhì)質(zhì)量分?jǐn)?shù)公式，可得30℃時(shí)溶液中溶質(zhì)的質(zhì)量為：（100g-17g）×20%=16.6g；
所以，60℃時(shí)的原溶液的溶質(zhì)質(zhì)量分?jǐn)?shù)為：×100%=33.6%．
答：60℃時(shí)的原溶液的溶質(zhì)質(zhì)量分?jǐn)?shù)為33.6%．
點(diǎn)評(píng)：本題主要考查溶液中溶質(zhì)質(zhì)量分?jǐn)?shù)的有關(guān)計(jì)算，計(jì)算時(shí)注意分析溶液質(zhì)量、溶質(zhì)質(zhì)量的變化．