Organic 2 Review Problem 55

Organic 2 Review Problem 55 - in order to grip the stirrer...

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METHODS AND MANIPULATION 39 by a pulley P, which is particularly useful if a number of stirrers are run off one revolving shaft. It is usually more convenient, however, to secure the stirrer S directly to the axis of a small motor, which is therefore clamped perpendicularly above. mA JT \ I FIG. 20. It is frequently necessary, however, to stir a solution which is boiling under reflux, and the stirrer must therefore be fitted with a seal to prevent the escape of vapour. This can often be done very simply by means of a short glass tube T (Fig. 20) which passes through the cork of the flask, and which serves as a collar within which the stirrer A fits quite closely. To prevent the escape of vapour, a short length of rubber tubing R (about 11 inches long) is fitted over the top of the tube T: the upper portion of this tube is then turned back over the stirrer as shown
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Unformatted text preview: in order to grip the stirrer securely. A few drops of glycerol or mineral oil placed between the upper portion of this tubing and the stirrer allow the latter to rotate freely with very little friction. Alternatively a mercury-sealed stirrer may be employed. Here again a short glass tube C is inserted through the cork of the flask to act as a collar for the stirrer. The tube C carries a short wide tube B which is either fused at its lower end to C, or is fixed to it by means of a cork as shown. The stirrer D carries a precisely similar tube E, the top of which however is now fixed to D: the bore of the tube E allows it to fit easily within the annular space between the collar C and the tube B. Mercury...
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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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