Question

What do you observe when you drop a few drops of acetic acid to test tubes containing

(a) phenolphthalein

(b) distilled water

(c) universal indicator

(d) sodium hydrogen carbonate powder

Answer 1

Acetic acid is a weak acid. The following changes occur when a few drops of acetic acid are added to the given solutions:-

(i) Phenolphthalein remains colourless, as acetic acid shows a change in colour in basic substances.

(ii) Acetic acid dissolves in distilled water.

(iii) Acetic acid turns the colour of the universal indicator to pale orange.

(iv) When added to sodium hydrogen carbonate powder, acetic acid causes effervescence because of the evolution of carbon dioxide gas in the process.

CH₃COOH(aq) + NaHCO₃(s) → CH₃COONa(aq) + H₂O(l) + CO₂(↑)