1、溶質(zhì)質(zhì)量分?jǐn)?shù)的概念:溶液中溶質(zhì)的質(zhì)量分?jǐn)?shù)是溶質(zhì)質(zhì)量與溶液質(zhì)量之比。
2、溶質(zhì)的質(zhì)量分?jǐn)?shù)計(jì)算:溶液中溶質(zhì)的質(zhì)量分?jǐn)?shù)可以用式表示如下:
3、溶液的稀釋問(wèn)題和濃縮問(wèn)題:
①關(guān)于溶液稀釋的計(jì)算:溶液稀釋前后,溶質(zhì)的質(zhì)量不變,若設(shè)濃溶液質(zhì)量為A g,溶質(zhì)的質(zhì)量分?jǐn)?shù)為a%,加水稀釋成溶質(zhì)的質(zhì)量分?jǐn)?shù)為b%的稀溶液B g,則A g×a%=Bg×b%(其中B=A+m水)
②關(guān)于溶液濃縮(無(wú)溶質(zhì)析出)的計(jì)算——溶液濃縮通常有幾種情況:
a、向原溶液中添加溶質(zhì):溶液增加溶質(zhì)前后,溶劑的質(zhì)量不變。增加溶質(zhì)后 初中地理,溶液中溶質(zhì)的質(zhì)量=原溶液中溶質(zhì)的質(zhì)量+增加的溶質(zhì)的質(zhì)量,而溶液的質(zhì)量=原溶液的質(zhì)量+增加的溶質(zhì)的質(zhì)量。若設(shè)原溶液質(zhì)量為A g,溶質(zhì)的質(zhì)量分?jǐn)?shù)為a%,加溶質(zhì)Bg后變成溶質(zhì)的質(zhì)量分?jǐn)?shù)為b%的溶液,則Ag×a%+Bg=(A g+Bg)×b%。
b、將原溶液蒸發(fā)去部分溶劑:溶液蒸發(fā)溶劑前后,溶質(zhì)的質(zhì)量不變。若設(shè)原溶液質(zhì)量為A g,溶質(zhì)的質(zhì)量分?jǐn)?shù)為a%,蒸發(fā)Bg水后變成溶質(zhì)的質(zhì)量分?jǐn)?shù)為b%的溶液,則:Ag×a%=(Ag一Bg)×b%。
c、與濃溶液混合:混合后的溶液的總質(zhì)量等于兩混合組分溶液的質(zhì)量之和,混合后的溶液中溶質(zhì)質(zhì)量等于兩混合組分的溶質(zhì)質(zhì)量之和。所以,設(shè)原溶液質(zhì)量為 A g,溶質(zhì)的質(zhì)量分?jǐn)?shù)為a%,濃溶液質(zhì)量為B g,溶質(zhì)的質(zhì)量分?jǐn)?shù)為b%,兩溶液混合后得到溶質(zhì)的質(zhì)量分?jǐn)?shù)為c%的溶液,則:Ag×a%+B g× b%=(Ag+Bg)×c%
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