Page 26 - PC 101 Interactive practical book

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

Notes

1. Dilution factor and difference in normality or molarity should be

considered in the calculation of concentration.

2. If the original sample is Solid, {Concn. = purity}, {unit of concn. should
be g% which means g analyte/100 g of sample powder} and {we divide by
the weight taken from the sample instead of the volume}.

E Ex xa am mp pl le e

Titration of 10 ml H 2SO 4 sample against 0.1 N NaOH, if the end point is 6 mL,

calculate the concentration of H 2SO 4 sample (M.W. of H 2SO 4 = 98).

Solution:

2 NaOH + H 2SO 4 → Na 2SO 4 + 2 H 2O

 1 NaOH ≡ ½ H 2SO 4

standard sample
Equivalence factor (F):

½ x M.W. of H 2SO 4 x 0.1
each ml of 0.1 N NaOH ≡ ≡ 0.0049 g H 2SO 4
1 x 1000

Concentration:

6 x 0.0049 x 1000
Concn. of H 2SO 4 = = 2.94 g/L
10

= 0.294 g%

Explanation

26 | P a g e