Page 30 - PC 101 Interactive practical book

MANSOURA NATIONAL UNIVERSIY
PHARM D- CLINICAL PHARMACY LEVEL I PHARM. ANAL. CHEM. I (PC 101)

P Pr ro oc ce ed du ur re e : :

1) Transfer 10 ml of NH 4Cl sample into a clean conical flask. (by bulb pipette 10 ml)

2) Add 50 ml of 1 N NaOH. (by bulb pipette 25 ml "2 times")

3) Boil for 10 min. inserting a funnel in the neck of the flask to avoid

evaporation of the solution.

After boiling, ensure that no more NH 3 is produced indicated by the

disappearance of ammonia odor.

4) Cool.

5) Add 2 drops M.O. indicator.

6) Titrate ≠ 1 N HCl.
{ Color change at E.P.: from Yellow to Orange }

C Ca al lc cu ul la at ti io on ns s : :

NH 4Cl + NaOH  boiling

 NaCl + NH 3 + H 20
1 st standard
NaOH + HCl  NaCl + H 20
2 nd standard

The equivalence factor (F) can be calculated on NaOH (1 standard) or on HCl
st
st
nd
(2 standard) but it is preferred to be calculated on the 1 standard.
Calculation of equivalence factor (F):

1 NaOH ≡ 1 NH 4Cl
standard sample
1 x M.W. of NH 4Cl x 1
each ml of 1 N NaOH ≡ ≡ ..................... g NH 4Cl
1 x 1000

Calculation of concentration:
(Blank reading – E.P.) x F x 1000
Concn. of NH 4Cl = = ................... g/L
10
Results:

E.P. =

Concn. =

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