DETECTION OF FORMALDEHYDE PRESENT IN GIVEN ORGANIC COMPOUND

Experiment No. 13: DETECTION OF FORMALDEHYDE PRESENT IN GIVEN ORGANIC COMPOUND

OBJECTIVE:

TO IDENTIFY THE ORGANIC COMPOUND PRESENT IN THE GIVEN ORGANIC SAMPLE

APPARATUS REQUIRED

1. Watch glass
2. Tong
3. Burner
4. Porcelain basin
5. Beaker
6. Test tube

CHEMICALS REQUIRED

• Given organic sample
• Blue and red litmus paper
• Other reagent

THEORY

Organic compounds are hydrocarbon and their derivatives. They are mainly made up of two parts- alkyl and functional group part. The functional group is defined as the atom or group of atoms that determines the characteristic properties of the organic compound. Some examples of functional groups are -OH, -CHO, -COOH, etc.

PROCEDURE

First of all, a preliminary test was performed. Then confirmatory test was done to identify the given organic compound.

OBSERVATION

1. Preliminary test:

a. Solubility: Soluble in water
b. Odour: Pungent
c. Colour: Colourless
d. Litmus paper test: Neutral
e. Residue test :

Experiment	Observation	Inference
Residue/Evaporation test: A few drops of the solution were evaporated on the watch glass over the water bath.	A solid residue was formed that gives a strong irritating smell with conc. H2SO4.	May be formaldehyde.

Confirmatory Test

Test of acetone

Experiment	Observation	Inference
1. Tollen’s test: 2 ml of original solution was taken in a clean and dry test tube and 2 ml of Tollens reagent was added to it. The solution was heated in a hot water bath for 4-5 minutes.	A silver mirror was formed in the inner wall of the test tube.	Presence of formaldehyde
2. Fehling’s test: 2 ml of the original solution was taken in a clean and dry test tube and 2 ml of Fehling’s solution was added to it and boiled.	Red ppt. was formed due to the formation of cuprous oxide.	Presence of formaldehyde.
3. Oxidation test: 2 ml of the original solution was taken in a clean and dry test tube and 2 ml of potassium dichromate solution was added to it. Then, 1 ml of conc. H2SO4 was added and then heated gently.	The orange colour of the potassium dichromate solution turned to green.	Presence of formaldehyde

Reactions involved

1. Tollen’s test

2. Fehling’s test

3. Oxidation test

RESULT

Hence, formaldehyde was found in the given solution.

CONCLUSION

Hence, organic compounds can be tested using specific reagents.

PRECAUTION

1. Apparatus should be handled carefully.
2. The sample should be taken in small amounts.
3. Heating should be done carefully.

Structure:

IUPAC name: Methanal
Common name: Formaldehyde