NOTE: E&OE, means errors and omissions are expected and accepted, in other words, if there is any error in the following art...
NOTE:
E&OE, means errors and
omissions are expected and accepted, in other words,
if there is any error in the following article, the same has to be corrected by
the user or the beneficiary accordingly.
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AIM:
Qualitative analysis for the identification of the phenolic functional group in
the organic sample.
SAMPLE:
An organic compound containing phenolic group.
(A)
PRELIMINARY TEST:
Color
– ( what color is it)
|
||
Physical
State – (the way the compound is formed up)
|
||
Odor
– (the smell it posses)
|
||
Ignition Test –
|
||
Experiment
|
Observation
|
Inference
|
A clean glass rod is
taken and dipped in the given sample.
The glass rod is then held at the mouth of the Bunsen flame.
|
Black sooty flame is
obtained.
|
The sample is aromatic
in nature.
|
(B) CONFIRMATORY TEST FOR THE IDENTIFICATION OF THE PHENOLIC
FUNCTIONAL GROUP:
TEST NO. 1
|
||
LITMUS TEST
|
||
Experiment
|
Observation
|
Inference
|
A drop of the sample is taken on
moist litmus paper.
|
Moist blue litmus paper turns red.
|
The sample is
acidic in nature.
|
TEST NO. 2
|
||
Sodium Carbonate (Na2CO3)
or Sodium Bicarbonate (NaHCO3)
|
||
Experiment
|
Observation
|
Inference
|
A pinch of sodium
carbonate/bicarbonate is added to a small amount of the sample taken in the
test tube.
|
No effervescence is
evolved.
|
The
sample is a weak acid, may be a phenol.
|
TEST NO. 3
|
||
Neutral Ferric Chloride
(FeCl3) Test
|
||
Experiment
|
Observation
|
Inference
|
To 0.5ml of the sample,
2-3 drops of neutral ferric chloride solution is
added.
|
A violet coloured complex is obtained.
|
Presence
of phenol in the sample is confirmed.
|
Preparation of Neutral Ferric Chloride (FeCl3)
solution –
To 1ml of the ferric chloride solution taken in a test tube
with dilute NH4OH is added dropwise until a reddish brown precipitate
is formed. Then, the FeCl3 solution is once again added dropwise
till the precipitate dissolves. This solution is called neutral ferric chloride.
TEST
NO. 4
|
||
Liebermann's
Test
|
||
Experiment
|
Observation
|
Inference
|
A
pinch of NaNO2 is added in a test tube along with 0.2ml of the sample
the test tube is heated gently until the NaNO2 melts.
To
the above solution concentrated H2SO4
is added dropwise. To the above solution,
water is added dropwise.
This
is followed by an excess of NaOH.
|
Deep
blue colour is obtained.
The solution turns red or reddish brown.
The solution turns deep green.
|
Presence
of phenolic group in the sample is confirmed.
|
TEST
NO. 5
|
||
Azo-Dye
Test
|
||
Experiment
|
Observation
|
Inference
|
In a
test tube, marked as ONE, a pinch
of NaNO2 is taken and distilled water is added to it. In the
second test tube, marked as TWO, a
solution of aniline in dilute HCl is prepared. In the third test tube, marked
as THIRD, a solution of sample in
dilute NaOH is taken and all three test tubes are immersed in an ice bath for
at least 5 minutes. The NaNO2 solution is then added to the
aniline solution with cooling immediately followed by the sample solution.
|
A
bright orange saffron colour precipitate is observed.
|
Presence
of phenolic group in the sample is confirmed.
|
REPORT: The presence of phenolic functional group present in
the sample is confirmed.
___________________________________________________________________
Know more about stuff related to this practical experiment
(Important for Boards):-
- Qualitative Analysisfor the Identification of the functional group in the Organic Sample Phenol
- Qualitative analysis for the identification of the functional group in the organic sample Acetic Acid (Example 1)
- Qualitative analysis for the identification of the functional group in the organic sample Benzoic Acid (Example 2)
- Qualitative Analysis for the identification of the Carboxylic functional group in the Organic Sample
- To find the molarity and strength of the given KMnO4 solution using M/20 standard Mohr salt solution
- How to find out the mass of salt required to achieve therequired concentration of a solution
- Viva Questions related to Qualitative Analysis
- Viva Questions related to Phenolic Functional Group
Reference:-
- Verma, Dr. N.K.. Comprehensive Practical Chemistry, Class XII.
- NCERT. Chemistry Part I and II, Class XII.
For latest syllabus, both theory and practical papers for
class XII, check out the CBSE’s official site http://cbseacademic.in/ for more info.
___________________________________________________________________
Related Questions-
Identification of organic compounds
Organic Chemistry Practical
Phenolic Compounds
How to prepare standard solution
How to prepare 250ml of solution
CBSE class 12 chemistry practicals
CBSE class XII chemistry practicals
Qualitative Analysis
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