🧪 Limit Test of Sulphate (Inorganic Chemistry Practical – Semester 1)

A Complete Lab Manual Style Practical for Pharma Students

🌟 Why This Practical is Important?

Limit Test of Sulphate is one of the most frequently asked practicals in:
✔ B.Pharm Semester 1
✔ D.Pharm Practical
✔ Viva & Internal exams

🎯 Aim

To determine whether the amount of sulphate impurity present in a given sample does not exceed the prescribed limit.

🧪 Principle (Easy Language)

Sulphate ions react with Barium chloride in acidic medium to form a white precipitate of barium sulphate.

👉 The turbidity produced in the test solution is compared with that of the standard solution.

⚗️ Chemical Reaction

$$SO_4^{2-} + BaCl_2 → BaSO_4 ↓ (White precipitate)$$

🧰 Apparatus Required

• Nessler cylinders (2)

• Measuring cylinder

• Pipette

• Glass rod

🧴 Reagents Required

• Barium chloride solution

• Dilute hydrochloric acid

• Sulphate standard solution

• Distilled water

🧪 Procedure (Step-by-Step)

🔹 Test Solution

1. Take sample solution in a Nessler cylinder

2. Add dilute HCl

3. Add barium chloride solution

4. Mix and allow turbidity to develop

🔹 Standard Solution

1. Take sulphate standard solution in another Nessler cylinder

2. Add dilute HCl

3. Add barium chloride solution

4. Mix and observe turbidity

👀 Observation

• Compare turbidity of test and standard side by side

• Observe against black background

✅ Result

✔ The sample passes the limit test for sulphate if turbidity of test solution is not greater than standard.

📋 Observation Table

Solution	Turbidity
Test	Slight / Equal
Standard	Standard turbidity

❓ Viva Voce Questions (Engagement Booster)

1. Why HCl is added in sulphate limit test?

2. What is the precipitate formed?

3. Why Nessler cylinders are used?

4. What happens if sulphate exceeds limit?

👉 Write answers in comments to test yourself!

🧠 Exam Tips for Students

✔ Always mention acidic medium
✔ Write chemical reaction
✔ Use words like turbidity comparison
✔ Draw diagram of Nessler cylinders (if asked)

🔗 Related Practicals (Internal Linking for Blog Growth)

• ✔ Limit Test of Chloride

• ✔ Limit Test of Iron

• ✔ Limit Test of Heavy Metals

• ✔ Limit Test of Arsenic

• ✔ Limit Test of Nitrate

• ✔ Limit Test of Boron

📌 Check previous posts for complete practical series.

🔜 Coming Next Practicals

➡️ Limit Test of Calcium
➡️ Limit Test of Magnesium
➡️ Semi-Micro Qualitative Analysis
➡️ Identification of Anions & Cation