Organic 2 Review Problem 18

Organic 2 Review Problem 18 - 2 P RACTICAL ORGANIC...

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2 PRACTICAL ORGANIC CHEMISTRY in just the proportion to give a sharp-melting eutectic mixture is so remote that this possibility may be neglected. [Occasionally arbitrary mixtures of two substances which (usually) are chemically related may melt fairly sharply at temperatures intermediate between the melting-points of the two components, but this phenomenon is rarely encountered.] B. Melting-point indefinite. (1) The substance is impure. This is almost invariably the cause of an indefinite melting-point. (2) The substance is pure , but on warming undergoes slight thermal decomposition before the melting-point is reached, and the decomposition products then act as impurities and depress the melting-point. Experimental Determination of Melting-point. The general method consists in placing the finely powdered compound in a capillary tube, and heating the latter in a bath of a suitable liquid, the temperature of the bath when the compound melts being then noted. The capillary tubes should be very thin-
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This note was uploaded on 09/19/2011 for the course CHM 2211 taught by Professor Castalleano during the Fall '06 term at University of Florida.

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