Activities 2.4 To Investigate the Properties of Ethanol

Aim :
To investigate the properties of alcohol

Procedure :
(A) Combustion of ethanol in air

1. About 1 cm3 of ethanol is added to an evaporating dish.
2. The ethanol is ignited using a lighted wooden splint.
3. The flammability of ethanol and the nature of the flame is observed.

(B) Oxidation of ethanol

1. The boiling tube is filled with approximately 5 cm3 of potassium dichromate(VI) solution, K2Cr2O7.
2. About 5 cm3 of dilute sulphuric acid is added to the potassium dichromate(VI) solution.
3. About 5 cm3 of ethanol is added to the acidified potassium dichromate(VI) solution.

4. A rubber stopper fitted with a delivery tube is inserted into the boiling tube. The delivery tube is inserted into a test tube placed in a beaker half-filled with ice cold water.

5. The mixture of ethanol and acidified potassium dichromate(VI) ios boiled slowly. The distillate is collected in the test tube.

6. The distillate is tested with a piece of blue litmus paper.
A colourless distillate is obtained.
The property of the distillate is acidic. It turns blue litmus paper red.

The orange colour of acidified potassium dichromate(VI) turns green.
The distillate has a vineger smell. Ethanoic acid is produced.

(C) Dehydration of ethanol

1. About 2 cm3 of ethanol is put into a dry test tube.
2. A small amount of glass wool is inserted into the test tube to absorb the ethanol.
3. Some porcelain chips are placed in the middle section of the test tube.

4. The test tube is closed with a rubber stopper fitted with a delivery tube. Another test tube is filled with water and inverted into a beaker.
5. The porcelain chips are heated strongly. The Bunsen burner flame is then shifted to the glass wool to vaporise the ethanol absorned in it.

6. The gas released is collected in two set test tubes.The following tests are carried out on the gas collected.

A) The flammability of the gas
B) The reaction of the gas with liquid bromine


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