Page 91 - Pharmaceutical_Analytical_Chemistry_1_Theoretical_Notes_Level_1

Mansoura National University
Pharm D-Clinical Pharmacy Program Level 1 Pharm. Anal. Chem. 1 (PC 101)

Determination of Na CO & NaHCO mixture
2 3 3
The principle depends on double-indicators (two-indicators) method.

st
1 Flask: Direct titration of the mixture ≠ stand. HCl using ph.ph. ind.
2-
E.P ≡ ½ CO
ph.ph. 3
nd
2 Flask: Direct titration of the mixture ≠ stand. HCl using M.O. ind.
Principle 2- -
E.P ≡ CO + HCO
M.O. 3 3
2-
2E.P ≡ CO
ph.ph 3
-
E.P - 2E.P ≡ HCO
M.O. ph.ph. 3
For Na CO :
2 3

Na CO + HCl → NaCl + NaHCO …….. Half neutralization
2 3 3
Equations NaHCO + HCl → NaCl + CO + H O …...Complete neutralization
3 2 2
Na CO + 2HCl → 2NaCl + CO + H O
2 3 2 2
For NaHCO : NaHCO + HCl → NaCl + CO + H O
3 3 2 2

For Na CO :
2 3

Titration

Curves:

For NaHCO :
3

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