Question

70℃時(shí)，氯化銨的溶解度為60g．一杯氯化銨溶液降溫到70℃時(shí)有晶體析出，則這杯溶液原來(lái)的溶質(zhì)質(zhì)量分?jǐn)?shù)可能是

1. A.
   30%
2. B.
   35%
3. C.
   37.5%
4. D.
   40%

Answer 1

D
分析：由題意，70℃時(shí)，氯化銨的溶解度為60g，一杯氯化銨溶液降溫到70℃時(shí)有晶體析出，則溫度高于70℃時(shí)，這杯溶液原來(lái)的溶質(zhì)質(zhì)量分?jǐn)?shù)應(yīng)大于70℃時(shí)飽和溶液中溶質(zhì)的質(zhì)量分?jǐn)?shù)，結(jié)合飽和溶液的溶質(zhì)質(zhì)量分?jǐn)?shù)=×100%，進(jìn)行分析解答．
解答：由題意，70℃時(shí)，氯化銨的溶解度為60g，一杯氯化銨溶液降溫到70℃時(shí)有晶體析出，則溫度高于70℃時(shí)，這杯溶液原來(lái)的溶質(zhì)質(zhì)量分?jǐn)?shù)應(yīng)大于70℃時(shí)飽和溶液中溶質(zhì)的質(zhì)量分?jǐn)?shù)．70℃時(shí)飽和溶液中溶質(zhì)的質(zhì)量分?jǐn)?shù)為100%=37.5%．
A、這杯溶液原來(lái)的溶質(zhì)質(zhì)量分?jǐn)?shù)大于37.5%，30%小于37.5%，故選項(xiàng)錯(cuò)誤．
B、這杯溶液原來(lái)的溶質(zhì)質(zhì)量分?jǐn)?shù)大于37.5%，35%小于37.5%，故選項(xiàng)錯(cuò)誤．
C、這杯溶液原來(lái)的溶質(zhì)質(zhì)量分?jǐn)?shù)大于37.5%，該選項(xiàng)等于37.5%，故選項(xiàng)錯(cuò)誤．
D、這杯溶液原來(lái)的溶質(zhì)質(zhì)量分?jǐn)?shù)大于37.5%，40%大于37.5%，故選項(xiàng)正確．
故選D．
點(diǎn)評(píng)：本題難度不大，掌握飽和溶液中溶質(zhì)質(zhì)量分?jǐn)?shù)的有關(guān)計(jì)算并能靈活運(yùn)用是正確解答本題的關(guān)鍵．