organic chem

An unknown compound melted at 131-133°C. It is thought to be one of the following compounds(mp,°C): trans-cinnamic acid (133-134); benzamide(128-130); DL-malic acid(131-133); or benzoin(135-137). The mixture melting points of the unknown compound with each of the test compounds are listed below. What is the unknown compound? Briefly explain your reasoning.

-trans-cinnamic acid...........110-120
-benzamide.....................130-132
-DL-malic acid..................114-124
-benzoin.........................108-116

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  1. With mixed melting points you look for the following two criteria:
    1. A sharp melting point (for example 110-120 is not anywhere near what I would call sharp)
    2. A melting point that is VERY close to the unmixed unknown.

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  2. benzamide

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