Estimation of sulpha drug

Aim: Determination the percentage purity of the given sample of a sulpha drug having molecular weight _________.

Requirement:

• Acetone
• 10 % sodium acetate
• Potassium dichromate solution (10%)
• Standard AgNO₃

Process: Weigh exactly about 0.2 gm of the given sample of sulpha drug and dissolve in a mixture of 25 ml Acetone & 20 ml 10 % sodium acetate solution (Warm it if necessary). Add 1 ml K₂Cr₂O₇ solution and titrate it against 0.1 ^N AgNO₃. At the end point yellow color of the solution is replaced by permanent faint red color. Perform the experiment in duplicate / triplicate.

Carry out the blank determination omitting the addition of the sulpha drug.

% purity of sulpha drug = $latex \frac{\left(V_1-V_2\right) \times N \times M \times 100}{W \times 1000} &s=2$

Where V₁  = ml of AgNO₃ used for sample

            V₂   = ml of AgNO₃ used for blank

             N   = Normality of AgNO₃ solution

             M   = Molecular weight of sulpha drug

             W   = weight of sample in gm.

Results: % purity of sulpha drug =                     

Observation:

• Blank Estimation:

Burette     : 0.1^N AgNO₃ solution

Flask         : 25 ml acetone + 20 ml 10 % CH₃COONa + 1 ml K₂Cr₂O₇ solution

End point : Yellow to faint red colour

• Actual Estimation:

Burette    : 0.1^N AgNO₃ solution

Flask        : 0.2 gm of sulpha drug + 25 ml acetone + 20 ml 10 % CH₃COONa + 1 ml K₂Cr₂O₇ solution

End point : Yellow to faint red colour

Chemical Reaction:

Calculation:

% purity of sulpha drug     =        $latex \frac{\left(V_1-V_2\right) \times N \times M \times 100}{W \times 1000} &s=2$

Where, V₁ = ml of AgNO₃ used for sample

             V₂ = ml of AgNO₃ used for blank

             N = Normality of AgNO₃ solution

             M = Molecular weight of sulpha drug

             W = weight of sample in gm.