因?yàn)槿苜|(zhì)質(zhì)量分?jǐn)?shù)=溶質(zhì)的質(zhì)量÷溶液的質(zhì)量*100％ 因?yàn)槿芤?溶質(zhì)+溶劑,所以溶劑質(zhì)量減少則溶液質(zhì)量減少,而溶質(zhì)質(zhì)量增加,則分母（溶液）變小,分子（溶質(zhì)）變大,所以質(zhì)量分?jǐn)?shù)變大.又因?yàn)轱柡腿芤旱脑?你不管再加多少溶質(zhì)它都不會(huì)溶解,溶質(zhì)質(zhì)量分?jǐn)?shù)使用被溶解的溶質(zhì)來(lái)算,最大就是恰好飽和時(shí)的溶質(zhì),所以溶質(zhì)質(zhì)量增加對(duì)整體無(wú)影響,但是溶劑質(zhì)量減小,所以分母變小,分子不變,結(jié)果還是變大,故如是飽和溶液,質(zhì)量分?jǐn)?shù)變大.