To study the following properties of acetic acid (ethanoic acid) - Science Practicals
Aim
To study the following properties of acetic acid (ethanoic acid):(i) odour
(ii) solubility in water
(iii) effect on litmus
(iv) reaction with sodium bicarbonate
Theory
Acetic add is present in vinegar. It can be obtained by wood tar distillation. It is sour in taste. Acetic acid has vinegar like smell. It turns blue litmus red but does not affect red litmus.
Acetic add is an organic acid. It belongs to carboxylic acid group because it has -COOH as functional group.
Acetic acid is soluble in water because it gets ionised in aqueous solution due to which it is acidic in nature.
CH3COOH (l) + H2O (l) → CH3COO- (aq) + H3O+ (aq)
Acetic acid reacts with sodium bicarbonate and gives brisk effervescence due to the formation of CO2 gas which turns lime water milky.
CH3COOH (l) + NaHCO3 (s) → CH3COONa + CO2 + H2O
Ca(OH)2 (aq) + CO2 (g) → CaCO3 (s) + H2O (l)
Acetic acid reacts with sodium bicarbonate and gives brisk effervescence due to the formation of CO2 gas which turns lime water milky.
CH3COOH (l) + NaHCO3 (s) → CH3COONa + CO2 + H2O
Ca(OH)2 (aq) + CO2 (g) → CaCO3 (s) + H2O (l)
Materials Required
Acetic acid, blue and red litmus paper or solution, sodium hydrogen carbonate (NaHCO3), lime water, test tubes.
| Experiment | Observations | Inference |
| Odour: A small amount of acetic acid is taken in a test tube and its odour is detected by wafting. | Pungent smell. | It has an irritating pungent smell. |
| Solubility in water: A small amount of water is taken in a test tube and a small amount of acetic acid is added to it and shaken well. | A homogeneous solution is formed. | Acetic acid is soluble in water. |
| Effect on litmus: A small amount of acetic acid is taken in a test tube and a strip of blue litmus paper is dipped in it. | Blue litmus turns red. | It is acidic in nature. |
| Reaction with sodium bicarbonate: A small quantity of sodium bicarbonate solution is taken in a boiling tube. The tube is corked with a double bore cork and a thistle funnel is inserted into the tube. Then a boiling tube is placed containing lime water near the tube containing NaHCO3 solution. One end of the delivery tube is inserted into the tube containing NaHCO3 solution and the other end is inserted into the tube containing lime water. Acetic acid is added into NaHCO3 solution through the thistle funnel and the change in colour of the lime water is observed. | A gas is evolved which turns lime water milky. | The gas produced is carbon dioxide due to the action of CH3COOH on NaHCO3, which turns lime water milky. |
Precautions
1.Do not inhale vapours of pure acetic acid. Handle it carefully.
2. Add little amount of Na2CO3 in acetic acid.