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The aim of this experiment is to study the physical and chemical properties of acetic acid (ethanoic acid).
Ethanoic acid (CH3COOH) is an organic acid containing (-COOH) functional group. It has an odour of vinegar. It turns blue litmus paper red and reacts with:
(a) Sodium hydrogen carbonate and sodium carbonate to evolve carbon dioxide gas
CH3COOH (l) + NaHCO3 (s) → CH3COONa (aq) + CO2 (g) + H2O (l)
2CH3COOH (l) + Na2CO3 (s) → 2CH3COONa (aq) + CO2 (g) + H2O (l)
(b) Sodium hydroxide to produce sodium ethanoate and water
CH3COOH + NaOH (aq) → CH3COONa (aq) + H2O
Apparatus and materials are required
Apparatus
- Round bottom flask
- Two beakers (100 ml)
- Test tubes
- Measuring cylinder (10 mL)
- Dropper
- Conical flask
- Thistle funnel
- Two bore cork
Chemicals
- Sodium carbonate (Na2CO3)
- Sodium bicarbonate(NaHCO3)
- Acetic acid (CH3COOH)
- NaOH solution
- Phenolphthalein indicator
- Distilled water
- Red litmus paper
- Blue litmus paper
To perform this experiment, steps to be followed in the following manner:
Procedure
- Add about 1 mL of the acetic acid in 2 mL of water in a test tube to check its solubility.
- Pick some drops of acetic acid using a glass rod and identify the nature of acetic acid using a litmus paper test.
- Take some amount of sodium carbonate in a round bottom flask and add, dropwise, the acetic acid from the thistle funnel to observe the neutralisation reaction.
- Observe the evolution of gas that occurs from the test tube.
- Similar observations can be seen for the reaction between sodium bicarbonate and acetic acid.
- Take 5 mL of acetic acid in a conical flask and add 2-3 drops of phenolphthalein indicator to it.
- Add NaOH dropwise to the conical flask until you observe the pink colour appear in the conical flask for neutralisation.
In this experiment, we learnt the physical and chemical properties of acetic acid.
- Acetic acid has a pungent odour with an irritating smell.
- Acetic acid readily dissolves in water and forms a homogeneous solution.
- Acetic acid turns blue litmus to red confirming its acidic nature.
- Acetic acid reacts with sodium carbonate as well as sodium bicarbonate to form the same products – sodium acetate, carbon dioxide and water. The CO2 is observed as effervescence.
- Acetic acid undergoes neutralisation reaction with sodium hydroxide and the reaction completion is indicated using phenolphthalein by pink colour.
FAQs on Properties of Acetic Acid
Q1: What is the use of acetic acid?
Answer: Acetic acid is used as a raw material and solvent in the production of other chemical products. Vinegar is an aqueous solution of acetic acid and trace compounds that may include flavorings. It is very helpful in creating the monomer for vinyl acetate. This molecule is a necessary ingredient in the creation of glue and acrylics.
Q2: What is the formula for acetic acid?
Answer: CH3COOH.
Q3: Which gas evolved when acetic acid reacts with sodium hydrogen carbonate?
Answer: When acetic acid reacts with sodium carbonate or sodium hydrogen carbonate, then the products formed are sodium ethanoate, water and carbon dioxide, which can be observed as effervescence.
CH3COOH(l) + NaHCO3(s) → CH3COONa(aq) + CO2(g) + H2O(l)
Q4: What is the effect of acetic acid on litmus paper?
Answer: Tests show that CH3COOH is acidic. When the litmus test is done, acetic acid turns blue litmus to red.
Q5: What is wafting?
Answer: Wafting is a process which involves moving a hand around the mouth of a container to push the fumes of a gas or odour of the chemical sample towards the nose.
JEE Main