PRACTICAL-PREPARATION & STADARDIZATION OF 0.1 N SULPHURIC ACID

Object – Preparation & standardization of Sulphuric acid (0.1 N)

Reference – 1. Kasture A.V. etal, Practical Pharmaceutical Chemistry-I, Nirali Prakashan, Pune, XI edition, 2005, 47

  1. Rao G.D., Practical pharmaceutical analysis, Birla publishers Pvt. Ltd., Delhi, II edition, 2007-08, 25

Glasswares & apparatus required – Volumetric flask, burette, burette stand, pipette, conical flask, digital balance, heating mantle.

Chemicals required – standard 0.1 N sodium carbonate solution (prepared by dissolving 530 mg of sodium carbonate in 100 ml of distill water), conc. Sulphuric acid, methyl orange solution

Theory – Sulphuric acid is a diprotic acid and 1 N solution contain 98.08/2 = 49.04 g H2SO4. Taking into consideration specific gravity (1.83) of sulphuric acid about 49.0 ml of conc. Sulphuric acid is required to prepare 1000 ml solution.

It is an example of alkalimetry. When a strong acid is titrated with a strong base, the salt produced in the reaction is not hydrolysed and therefore the ph of the resultant solution at the end point is exactly 7.0. sulphuric acid is a strong acid, is standardized by titrating with a strong base i.e. sodium carbonate (primary standard). The following reaction takes place when sodium carbonate is titrated with sulphuric acid. In this titration, end point detection is carried out by using methyl orange indicator.

Procedure –

In a volumetric flask, 4.9 ml of conc. Sulphuric acid was taken and 900 ml water was slowly added, cooled and then the volume was made upto 1000 ml with water.

Standardization –

  1. 10 ml of 0.1 N Sodium carbonate solution was pipette out into a clean and dried conical flask.
  2. 2 drops of methyl orange indicator was added to it.
  3. The contents of the flask was now titrated with sulphuric acid until red color was obtained.
  4. Burette reading was taken.

Observation table –  

S.NO. VOLUME OF 0.1 N SOD. CARBONATE SOLUTION TAKEN INITIAL BURETTE READING FINAL BURETTE READING VOLUME OF 0.1 N SULPHURIC ACID CONSUMED
1 10 ML 50 38 12 (SUPPOSE)

 

 

Calculation – Normality of H2SO4  is calculated by-

N1V1 = N2V2

N1 = 0.1 N = Normality of Na2CO3 Solution, N2 = ? = Normality of H2SO4

V1 = 10 ml = Volume of Na2CO3 Solution, V2 = 30 ml = Volume of H2SO4

0.1 X 10 = N2  X 12

Or N2 = 1 / 12 = 0.08 N

Result – Sulphuric acid (0.1 N) was prepared and standardized. The exact normality was found to be 0.08 N

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