Percentage Purity of Sulphuric Acid

 

Process:

ð  Weigh 2 g of the sample accurately in weighing bottle.

ð  Transfer the same sample in a 500 ml. volumetric flask.

ð  Made the solution up to 500 ml. with distilled water.

ð  Pipette out 10 ml. from the same solution using volumetric pipette and transfer it into a conical flask.

ð  Add 2 – 3 drops of phenolphthalein indicator.

ð  Titrate it against 0.1(1/10)N NaOH (sodium hydroxide).

   

Chemical Reaction:

2NaOH_(aq) + H₂SO_{4 (aq)} à Na₂SO_{4 (aq)} + 2H₂O_(aq)

Calculation:

            1000 ml 1 NaOH   ≡  49 g H₂SO₄

1000 ml 0.1 N NaOH   ≡  4.9 g H₂SO₄

1 ml 1 N NaOH  ≡  0.0049 g H₂SO₄

 

% Purity =  Burette Reading (BR) X Eq.Wt.

                                            4

 % Purity =  (BR) X 49

                           4

 % Purity =  (BR) X 12.25

                     

Answer: % Purity of H₂SO₄ is (BR) X 12.25