Organic 2 Review Problem 453

Organic 2 Review Problem 453 - QUANTITATIVE ANALYSIS 437...

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QUANTITATIVE ANALYSIS 437 For liquid compounds, a very thin-walled glass bulb, of ca. 3-5 mm. diameter, similar to that shown in Fig. 75 (p. 422) is prepared, and the stem cut off about 5 mm. from the bulb. The bulb is then weighed, and the liquid introduced through a fine capillary tube inserted down the stem into the bulb. If the liquid is not appreciably volatile, the bulb can then be weighed: if the liquid is volatile, the bulb before weighing should be held in light tongs or tweezers, and the stem quickly sealed in a small flame. When the freezing-point of the pure solvent has been determined, the bung with the thermometer and stirrer must be lifted out of the tube, and the bulb dropped in. The stirrer may not be sufficiently robust subsequently to break the bulb: in this case, the bulb should be broken by a thick glass rod, the solution well stirred, the rod withdrawn, and the thermomenter and stirrer promptly replaced. Although in general a Beckmann thermometer should not be withdrawn from the liquid at any
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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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