Question

What will you observe when you drop a few drops of acetic acid to a test tube containing :
a) Phenolphtalein c) distilled water
b) universal indicator d) Sodium hydrogen carbonate

Answer 1

HEYY THERE!

When you add acetic acid (CH₃COOH) on A, B, C, and D, the following happens:

A. Phenolphtalein:
Colour of phenolphthalein is colourless. In presence of acids, they remain colourless. Hence, there is no observation when acetic acid is dropped on phenolphthalein. Thus, it remains colourless.


B. Universal indicator
Blue (moist) litmus paper turns red. Acetic acid turns methyl orange pink. Again, with a pH scale, it gives a value below 7 (because it is acidic).


C. Distilled water
When you add few drops of Acetic acid, it besides increasing the concentration due to release of H⁺ from its molecule, will also force a neutral Water molecule to dissociate into H⁺ ions and OH⁻ ions. Thus, there is an increase in the concentration of H⁺ and the solution becomes acidic and the pH lowers down less than 7.


D. Sodium hydrogen carbonate
It is a characteristic of all acids, to liberate carbon dioxide gas when they react with carbonate or bicarbonate salts. Thus, when acetic acid is dropped in a test tube containing sodium bicarbonate, brisk effervescence takes place because Carbon dioxide gas bubbles out.

Reaction: CH₃COOH + NaHCO₃ ---------> CH₃COONa + H₂O + CO₂





THANKS!

Answer 2

a) Phenolphthalein remains colourless
b) As distilled water is neutral there is no change in the acetic acid
c) Acetic acid turns the universal indicator to pale orange
d) Sodium hydrogen carbonate + Acetic acid 》Carbondioxide + Other substances....


HOPE IT HELPS.

THANKS