2. Liquid Sample (Formic acid, Acetic acid)¶

2.1. Physical Character¶

State of aggregation

Appearance

Color

Smell

Experiment	Observation	Inference
Heat a small portion of the sample in a test tube	Evaporates with pungent smell	May be acetic acid or formic acid
Treat a small portion of the sample with conc. sulfuric acid and warm gently if necessary.	Smell of vinegar Evolves a gas on burning of which, shows pale blue flame	May be acetic acid May be formic acid

Experiment	Observation	Inference
Shake a small portion of the sample with fresh water in a test tube	Sample is soluble in water	May acetic acid or formic acid

Experiment

Observation

Inference

Test a portion of the aqueous solution or suspension with

May be formic acid or acetic acid

From the experiments, solubility and acidity it appears that the given sample is Formic acid or Acetic acid.

Experiment	Observation	Inference
Add 2 ml silver nitrate solution to 2 to 3 ml cold aqueous neutral solution of original sample. (Preparation of neutral solution: Add excess ammonium hydroxide solution to 1 ml. of OS. Boil the mixture until it remains inactive towards red litmus paper. Add water to make the volume 4-5 ml	Liquid becomes brown to gray. A white precipitate appears.	May be formic acid May be acetic acid

Experiment	Observation	Inference
Cacodyl oxide test: Strongly head 1ml original sample with small amount of arsenic trioxide and potassium hydroxide to dryness	Extremely bad odor	Acetic acid

Treat a small amount of the neutral solution of O.S. with mercuric chloride solution.

White precipitate appears which turns to gray on warming in presence of excess neutral solution

Formic acid

Name of the given compound

Structure of the given compound