Learn the limit test for chlorides in sodium bicarbonate through a laboratory experiment or practical.
Aim:
To perform the limit test for chlorides for the given sample and report its compliance /non-compliance with standards of I.P.
Sample: Sodium bicarbonate
Requirements:
Glasswares and miscellaneous: Nessler cylinders, measuring cylinder, pipette, pipette bulb, dropper, test-tube stand, glass rod, volumetric flask, and balance.
Chemicals: Sodium bicarbonate (NaHCO3), silver nitrate (AgNO3), nitric acid (HNO3), and sodium chloride (NaCl).
Principle:
We already discuss the principle of the limit test for chloride in the previous article. Click here to get the detailed reaction involved in this test.
Preparation of reagents:
Preparation of dilute HNO3:
Click here to get the procedure.
Preparation of 0.1M AgNO3:
Click here to get the procedure.
Preparation of 25 ppm standard NaCl solution:
Click here to get the procedure.
Procedure:
Standard opalescence:
- Take 10.00 ml of 25 ppm chloride standard solution using a pipette into a Nessler cylinder and label it as standard.
- Add 05.00 ml of water.
- Add 10.00 mL of dilute HNO3 solution to the above preparation and dilute to 50 ml with water.
- Then add 01.00 ml of prepared 0.1 M silver nitrate solution.
- Stir immediately with a glass rod and let stand for five minutes by protecting from light.
- Observe this standard preparation under a black background.
Test opalescence:
- Take 01.20 gm of sodium bicarbonate into a Nessler cylinder and label it as a test.
- Add 02.00 ml of dilute HNO3 solution to the above preparation and dilute to 50 ml with water.
- Then add 01.00 ml of prepared 0.1 M silver nitrate solution.
- Stir immediately with a glass rod and let stand for five minutes by protecting from light.
- Observe this standard preparation under a black background.
Observations:
The test solution produces less or same or more opalescence than the standard solution.
Results:
The sample passes/fails the limit test as per Indian Pharmacopoeia.
FAQ (Frequently Asked Questions)
Which precipitate is obtained in the limit test for chloride?
The reaction of the Cl- with AgNO3 in the presence of weak HNO3 produces a silver chloride precipitate as a limit test for chloride.
Which acid is used in the limit test of chloride?
Nitric acid is used in the chloride limit test, which makes the solution acidic and aids silver chloride precipitation, which causes the solution to become turbid at the end of the process.
Which standard solution is used for the limit test of chloride?
Standard sodium chloride solution of specific concentration (PPM) is used for limit test of chloride.
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