Organic 2 Review Problem 100

Organic 2 Review Problem 100 - evolved in F during the...

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84 PRACTICAL ORGANIC CHEMISTRY The liquid becomes progressively darker in colour, and then effervesces gently as ethylene is evolved. Allow the gas to escape from the delivery-tube in T for several minutes in order to sweep out the air in F and B. Now fill a test-tube with water, close it with the finger, and invert the tube in the water in T over the delivery-tube so that a sample of the gas collects in the tube. Close the tube again with the finger, and then light the gas at a Bunsen burner at a safe distance from the apparatus. If the tube contains pure ethylene, the latter burns with a clear pale blue (almost invisible) flame: if the ethylene still contains air, the mixture in the test-tube ignites with a sharp report. Allow the FIG. 56. gas to escape from the delivery-tube in T until a sample tested in this way proves to be pure ethylene. Then collect 3-4 gas-jars of ethylene, closing each one under water with a slightly greased glass plate. Since appreciable quantities of. sulphur dioxide are
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Unformatted text preview: evolved in F during the later stages of the reaction, disconnect the delivery-tube joining F to B, and then turn out the gas. Carry out the following tests with the jars of ethylene. (1) Odour. Smell the contents of one of the jars. The ethylene has a characteristic sweetish odour. Ethylene when deeply inhaled produces temporary anaesthesia which is almost devoid of unpleasant after-effects; hence it has been used for dental surgery, minor operations, etc. (2) Bromine. Slip slightly to one side the glass plate covering one jar of ethylene, add 2-3 ml. of bromine water (preparation, p. 525), restore the glass plate in position, and then shake the jar vigorously. The colour of the bromine rapidly disappears as i,2-dibromoethane is formed. Note that owing to the absorption C 2 H 4 + Br 2 = C 2 H 4 Br 2 of ethylene, a partial vacuum now exists in the jar....
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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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