Page 33 - PC 101 practical notes 24-25..

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

{ Color change at E.P.: from Red to Orange }

b) For the total mixture [NH 4Cl & HCl]: (E.P total)

1) Transfer another 10 ml of the mixture into a clean conical flask.

2) Add 5 ml neutral formalin. (by measuring cylinder )

!!!!!! Caution: Formalin is very toxic !!!!!!
3) Leave for 5 minutes. (to make the reaction completed)

4) Add 10 drops ph.ph. indicator. measuring cylinder

5) Titrate ≠ 0.1 N NaOH.

Color change at E.P.:

from Colorless to first pink persistent for 30 sec.

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

E.P HCl ≡ HCl only

E.P total ≡ HCl + NH 4Cl

 (E.P total - E.P HCl) ≡ NH 4Cl only

For HCl :

HCl + NaOH ⎯→⎯ NaCl + H 20

 1 NaOH ≡ 1 HCl
standard sample

Equivalence factor (F):

1 x M.W. of HCl x 0.1
each ml of 0.1 N NaOH ≡ ≡ .......... g HCl
1 x 1000

Concentration:

E.P HCl x F x 1000
Concn. of HCl = = .......... g/L
10

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