How to identify that given compound is aldehyde?

Scheme for identification of aldehyde

1) Physical Appearance:

Methanal is a gas , Ethanal is a volatile liquid and aldehydes upto carbon number 11 are liquid and still higher members are solids.

2) Odour:

Lower members of aldehydes have pungent odour while many higher aldehydes have pleasant odour.

3) Acidity or Basicity:

Aldehyde have no effect to litmus paper.

4) Solubility:

Aldehydes upto four carbons are miscible with water however solubility of aldehydes in water decreases rapidly on increasing length of alkyl chain. Aldehydes are soluble in organic solvents.

5) Boiling Point:

Boiling point of aldehydes are higher than those of non-polar compounds

( hydrocarbons) and weakly polar compounds of comparable molecular masses.

6) Chemical Tests:

With Benedict's Solution and Fehling's Solution , aldehydes form brick red precipitates of Cu²O.

. Aldehydes also gives silver mirror test witn Tollen's Reagent.

7) Unsaturation:

In 2ml of aldehyde , add 1% alkaline potassium permanganate solution dropwise and observe the solution if it persist pink colour then the aldehyde is saturated but if pink colour disappear the aldehyde is unsaturated.