Page 13 - PC 101 practical notes 24-25..

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

2+ 2- 3+ 3-

CaCO3 Na3PO4

Equiv. wt. = M.W. of CaCO3/2 Equiv. wt. = M.W. of Na3PO4/3

Advantage of using normal concentration: Very Important

The main advantage of using normal concentration over molar ones is

the simple 1:1 ratio involved in all reactions of the same type and that

facilitates our calculations.

ex. 1 equiv. wt. of NaOH ≡ 1 equiv. wt. of HCl i.e. In a certain type of
reactions, equivalent weights
≡ 1 equiv. wt. of H 2SO 4 of all substances are
equivalent in their reactive
≡ 1 equiv. wt. of H 3PO 4 powers because they are all

referred to a common
+
≡ 1 mole of H standard [Hydrogen].

In other words: Solutions having the same normality react in 1:1 ratio.

ex. 1 L of 1 N NaOH ≡ 1 L of 1 N HCl ≡ 1 L of 1 N H2SO4 ≡ 1 L of 1 N H3PO4 ,

10 ml of 0.2 N NaOH ≡ 10 ml of 0.2 N HCl ≡ 10 ml of 0.2 N H2SO4 ≡ 10 ml of 0.2 N H3PO4

Remember: [=] means equal while [ ≡ ] means equivalent.
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