MCAT Question of the Day
    •

    Q:

    		 An azeotrope is a mixture of two or more liquids which distill together as if they were a single compound. Ethanol and water form an azeotrope, making it difficult to purify ethanol. Addition of benzene can help to solve this problem: benzene, ethanol, and water boil at a ratio of 7:17:76 water:ethanol:benzene. This leaves behind almost all of the excess ethanol. During a distillation, you work with a mixture whose ratio is 7:20:76. What remains after the water:ethanol:benzene azeotrope has boiled off?
    		 

    A

    		 3 parts ethanol

    B

    		 Everything; the azeotrope will not boil if the liquids are not in the correct proportions.

    C

    		 Nothing; the azeotrope will adjust to accommodate the extra 3 parts of ethanol

    D

    		 This this cannot be determined based on the starting ratios because adjustments to the starting proportions can have unpredictable consequences on the ratio at which the azeotrope will boil.



    Separation and Purification | Quantitative Skills |
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