Organic 2 Review Problem 491

Organic 2 Review Problem 491 - Q UANTITATIVE A NALYSIS 4 75...

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QUANTITATIVE ANALYSIS 475 mg. If either or both have changed by more than this amount, the whole process is repeated until each shows no further gain in weight (of more than o-i mg.). One of the dangers in burning out a combustion tube is that of burning it out too thoroughly; so that when a substance is then ignited in it, the results obtained will be low as the tube filling will take up as much carbon dioxide and water vapour as it requires in order to come to equilibrium at the furnace and thermostatic mortar temperatures. This difficulty is overcome by doing two or three "equilibrium" combustions of known substances in a new combustion tube, after it has been burnt out and before a real estimation is carried out in it. The combustion tube thus has opportunity to come to equilibrium and the water absorption tube may also pick up the very small quantity of carbon dioxide that it normally retains. The operations leading up to the carrying out of a combustion will now be described.
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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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