#DETERMINATION OF PARTITION COEFFICIENT OF BENZOICACID ACID BETWEEN OIL AND WATER
Aim:
To determine the partition coefficient of
benzoic acid between oil and water.
Apparatus:
Separating funnel, burette, pipette,
conical flask, Beaker.
Chemicals used:
0.1N NaOH solution, potassium hydrogen phthalate,
benzoic acid, peanut (or) arachis oil, water, phenolphthalein indicator.
Theory:
Nernst distribution law states that
when added substance is insufficient to saturate immiscible liquids the solute
distributes between liquids. In such a way that at equilibrium the ratio of concentration
of the solute on the two liquids is constant at constant temperature partition
coefficient may be defined as the ratio of solute in organic phase to that of aqueous
phase.IfC0 and are CW equilibrium concentration of
substance in organic phase and aqueous phase respectively then the expression
of
Kd
= C0/CW
Where
the equilibrium constant kdis called partition coefficient
This
equation also called distribution law.
Procedure:
Take
30ml of oil to this add 1gm of benzoic acid and add 30ml of water. Shake
contents of separating funnel for 30 minutes then separate aqueous and oil layer
and titrate with 0.1N NaOH solution respectively. calculate the benzoic acid in aqueous and oil phase and
calculate partition coefficient from formulae
Kd = C0/CW
Observations:
Standardization
of 0.1N NaOH:
Contents in
the conical flask
|
Burette
readings
|
Volume
consumed
|
||
Initial(ml)
|
Final(ml)
|
|||
0.2
g of PHP + 10ml of water + 2 drops of
phenolpthalein
|
0
|
|
|
|
1ml of 0.1 N
NaoH ≡ 0.2042 g of PHP
-------ml of
NaoH ≡ 0.2042 g of PHP
Contents in
the conical flask
|
Burette readings
|
Volume consumed
|
||
Initial(ml)
|
Final(ml)
|
|||
5ml of aqueous
titrate + 2 drops of phenolpthalein indicator.
|
0
|
|
|
|
|
-------ml
of ----- N NaoH ≡ ------g of Benzoic
acid
Determination
of benzoic acid in organic layer :
Contents in
the conical flask
|
Burette
readings
|
Volume
consumed
|
||
Initial(ml)
|
Final(ml)
|
|||
5ml of aqueous
titrate + 2 drops of phenolpthalein indicator.
|
0
|
|
|
|
1ml of 0.1 N NaoH ≡ 0.0122g of Benzoic acid
-------ml of ----- N NaoH ≡ ------g of Benzoic acid
Report:
The partition coefficient of benzoic acid in oil and water was found to be -------- gm
& -------gm
Then Kd
= C0/CW = ------
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