Experiment No. 2: Limit Test for Sulphates

Aim:

To perform the limit test for sulphates as per Indian Pharmacopoeia.

Principle:

The limit test for sulphates is based on the reaction of sulphate ions with barium chloride in the presence of dilute hydrochloric acid, producing a white turbidity of barium sulphate.

The turbidity developed in the test solution should not be greater than that produced in the standard solution.

Requirements:

• Test solution (substance under test)

• Standard potassium sulphate solution

• Barium chloride solution

• Dilute hydrochloric acid

• Nessler cylinders

Procedure:

1. Take 1 ml of the test solution in a Nessler cylinder.

2. Add 1 ml of dilute hydrochloric acid.

3. Add 1 ml of barium chloride solution.

4. In another Nessler cylinder, prepare a standard solution in the same way (using potassium sulphate).

5. Mix the contents well and allow to stand for 5 minutes.

6. Compare the turbidity of the test solution with that of the standard solution.

Observation:

The turbidity of the test solution is not more than that of the standard solution.

Result:

The sulphate content in the given sample is within the official limit. ✅

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Note for Students:

✨ Always record your observation clearly in the observation table.

✨ Draw neat diagrams (if required) to make your record attractive.

✨ Don’t forget to write precautions at the end.

📌 This is part of our Pharmaceutical Inorganic Chemistry Practical Book series.

Next, we will cover: Limit Test for Iron.

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