Acetic Acid Properties Experiment Notes

CLASS X EXPERIMENT 5: Acetic Acid Properties

Aim

  • To study the properties of acetic acid (ethanoic acid):

    • Odour

    • Solubility in water

    • Effect on litmus

    • Reaction with sodium bicarbonate

Theory

  • Acetic acid is sour in taste.

  • It has a vinegar-like smell.

  • It turns blue litmus red but does not affect red litmus.

  • Acetic acid is an organic acid that belongs to the carboxylic acid group.

  • The functional group of acetic acid is -COOH.

  • Acetic acid is soluble in water because it gets ionized in an aqueous solution, which makes it acidic.

  • Ionization of acetic acid in water:
    CH3COOH (l) + H2O (l) \rightarrow CH3COO^- (aq) + H3O^+ (aq)

  • Acetic acid reacts with sodium bicarbonate (NaHCO3) to produce brisk effervescence.

  • The effervescence is due to the formation of carbon dioxide (CO2) gas.

  • CO2 gas turns lime water milky.

  • Reaction of acetic acid with sodium bicarbonate:
    CH3COOH (l) + NaHCO3 (s) \rightarrow CH3COONa + CO2 + H2O

  • Reaction of carbon dioxide with lime water:
    Ca(OH)2 (aq) + CO2 (g) \rightarrow CaCO3 (s) + H2O (l)

Materials Required

  • Acetic acid

  • Blue and red litmus paper or solution

  • Sodium hydrogen carbonate (NaHCO3)

  • Lime water

  • Test tubes

Observations and Results

Odour

  • Observation: Acetic acid has a vinegar-like odour when a small amount is taken in a test tube and wafted.

  • Inference: Acetic acid has a vinegar-like odour.

Solubility in Water

  • Observation: Acetic acid forms a homogeneous solution when a small amount is added to water and shaken well.

  • Inference: Acetic acid is soluble in water.

Litmus Test

  • (a) Blue Litmus

    • Observation: Blue litmus solution turns red when added to acetic acid.

    • Inference: Acetic acid is acidic in nature.

  • (b) Red Litmus

    • Observation: No change in colour when red litmus solution is added to acetic acid.

    • Inference: Acetic acid is acidic in nature.

Reaction with Sodium Hydrogen Carbonate (Sodium Bicarbonate)

  • (a) Reaction with NaHCO3

    • Observation: A colourless, odourless gas is produced with brisk effervescence when sodium bicarbonate is added to acetic acid.

    • Inference: Acetic acid liberates CO2 when treated with sodium bicarbonate.

  • (b) Passing Gas Through Lime Water

    • Observation: Lime water first turns milky and then becomes clear upon passing more gas.

    • Inference: Acetic acid liberates CO2 when treated with sodium bicarbonate.

Precautions

  • Do not inhale vapours of pure acetic acid; handle it carefully.

  • Add a little amount of NaHCO3 in acetic acid.