Tests

CHEMISTRY                                                                                                                                                                              HOME

 

Organic Chemistry Tests:

 

Test for Alkenes- 

 

Bromine Water:- Orange --> colourless

 

Acidified Potassium Permanganate (vii) :- Purple --> colourless (Alkaline or neutral turns from purple to brown)

 

Test for Aldehyde-

 

Benedict’s Solution (Or Fehling’s solution):- Blue --> Brick Red

 

test for Carboxyilic acid-

 

Sodium Carbonate solution:- Effervescence

 

 

Bromine Water

Potassium Permanganate

Benedict’s solution

Sodium Carbonate solution

Alkanes

X

X

X

X

Alkenes

YES

YES

X

X

Aldehydes

X

X

YES

X

Ketones

X

X

X

X

Carboxylic acids

X

X

X

YES

 

Explanation:-

 

Alkanes

 

Alkanes are relatively unreactive. Because they don’t have a double bond, they can’t participate in addition reactions.

 

Alkenes

 

Because of the double bond are easily oxidised. They form 1,2-dibromoethane with bromine water (Colourless) and ethane-1,2-diol with potassium permanganate (Also colourless).

 

Aldehydes

 

Aldehydes are reducing agents. The reduce the blue Copper (II) ions to brick red Cu (I) oxide.

 

Ketones

 

Are not reducing agents, and do not produce a colour change in benedict’s.

 

 

 

Carboxylic Acids

 

Being acids, they are the only ones that neutralise a base. This neutralisation can be easily viewed by the effervescence of a carbonate.