Page 28 - PC 101 practical notes 24-25..

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

Exp.: Determination of NH 4Cl sample

# NH 4Cl is acidic because it is a salt of strong acid (HCl) & weak base (NH 4OH).

# NH 4Cl is determined by 2 methods:

1) Back (Residual) titration method.

2) Formol method [specific method for ammonium salts].

A A) ) D De et te er rm mi in na at ti io on n o of f N NH H4C Cl l s sa am mp pl le e b by y b ba ac ck k t ti it tr ra at ti io on n
4

P Pr ri in nc ci ip pl le e : :

NH 4Cl + NaOH ⎯ ⎯ ⎯→ NaCl + NH 3 + H 20
boiling
(sample) known excess
of st. NaOH
(50 ml)
It depends upon boiling the ammonium salt with a known excess of

standard alkali (NaOH) producing ammonia which is removed by boiling. Then

the remaining unreacted part of NaOH is back titrated against standard HCl

using M.O. or ph.ph. indicator.

NaOH + HCl ⎯→ NaCl + H 20
⎯
remaining standard
unreacted titrant
part

N No ot te es s: :

1) Boiling is necessary for the reaction between NH 4Cl and NaOH to

remove the produced ammonia.

2) This method requires Blank Determination which is a separate

determination in which we repeat the same steps of the experiment

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