[化學] 91年台大普化(C)--關於依數性質

[bslh ( 想念高雄的太陽)]

 第17題

 two aqueous solution are prepared:2.0m Cu(NO3)2   2.0m NaBr
 which statement is true?
 (A) Cu(NO3)2 solution has higher vapor pressure and lower freezing point
     than NaBr solution
 (B) Cu(NO3)2 solution has higher vapor pressure and higher freezing point
     than NaBr solution
 (C) Cu(NO3)2 solution has lower vapor pressure and lower freezing point
     than NaBr solution
 (D) Cu(NO3)2 solution has lower vapor pressure and higher freezing point
     than NaBr solution

 依照熔點下降的公式來看，可以確定B D是錯的
 那A C要怎麼判斷才好?

 蒸氣壓下降，
 是只要照著公式 △P= i x (純溶劑的蒸氣壓) x (溶質的莫耳分率) 考量嘛?




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推 siccreater:應該就是這樣判斷 我覺得是C
推 vivaonly:蒸氣壓越大的沸點越低