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What is the purpose of adding dilute nitric acid in the limit test for chloride?
What is the purpose of adding dilute nitric acid in the limit test for chloride?
- To increase the solubility of chloride.
- To make the solution acidic and help silver chloride precipitation. (correct)
- To oxidize any organic impurities.
- To neutralize the solution.
The limit test for chloride relies on the formation of silver chloride ($AgCl$) precipitate, which appears as opalescence in the solution.
The limit test for chloride relies on the formation of silver chloride ($AgCl$) precipitate, which appears as opalescence in the solution.
True (A)
In the limit test for chloride, what apparatus are used?
In the limit test for chloride, what apparatus are used?
Nessler's cylinder, Nessler's cylinder stand, glass rod, and measuring cylinder
In the reaction during the limit test for chloride, soluble chloride reacts with ______ in the presence of dilute nitric acid to form opalescence.
In the reaction during the limit test for chloride, soluble chloride reacts with ______ in the presence of dilute nitric acid to form opalescence.
Why is it important to compare the opalescence of the test solution with that of a standard solution in the limit test for chloride?
Why is it important to compare the opalescence of the test solution with that of a standard solution in the limit test for chloride?
Tap water is recommended for use in the limit test for chloride to ensure accurate results.
Tap water is recommended for use in the limit test for chloride to ensure accurate results.
Match each reagent with its role in the limit test for chloride:
Match each reagent with its role in the limit test for chloride:
What observation indicates that the given sample fails the limit test for chloride?
What observation indicates that the given sample fails the limit test for chloride?
A 5 ppm standard chloride solution is prepared by diluting 1 ml of 0.0824% w/v with ______ ml of distilled water.
A 5 ppm standard chloride solution is prepared by diluting 1 ml of 0.0824% w/v with ______ ml of distilled water.
In the test solution preparation for magnesium trisilicate, what are the steps taken after boiling 2g of it with distilled water and nitric acid?
In the test solution preparation for magnesium trisilicate, what are the steps taken after boiling 2g of it with distilled water and nitric acid?
Flashcards
Limit test for chloride
Limit test for chloride
A test to determine the amount of chloride impurities in a given sample.
Silver nitrate
Silver nitrate
Reacts with soluble chloride in the presence of dilute nitric acid to form opalescence of silver chloride.
Dilute nitric acid in chloride test
Dilute nitric acid in chloride test
Used to make the solution acidic and help in the precipitation of silver chloride.
Opalescence in the chloride limit test
Opalescence in the chloride limit test
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Standard chloride solution
Standard chloride solution
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Study Notes
- The aim is to perform the limit test for chloride in a given sample.
- Apparatus required includes a Nessler's cylinder, Nessler's cylinder stand, glass rod, and a measuring cylinder.
- Chemicals needed are standard chloride solution, dilute nitric acid, 0.1 M silver nitrate solution, distilled water, and the sample.
Preparation of Solutions
- Standard chloride solution (5 ppm): Dilute 1 ml of 0.0824% w/v with 100 ml distilled water.
- Standard chloride solution (25 ppm): Dilute 5 ml of 0.0824% w/v with 100 ml distilled water.
- Dilute nitric acid (10%): Dilute 10.6 ml of concentrated nitric acid with 100 ml of distilled water.
- Silver nitrate solution (0.1M): Dilute 1.7 gm of silver nitrate with 100 ml of distilled water.
Sample Solutions for Chloride Limit Test
- Calcium carbonate: Dilute 1.0 gm of calcium carbonate in 3 ml of nitric acid and increase the volume to 10 ml with distilled water.
- Calcium gluconate: Dilute 1.0 gm of calcium gluconate with 40 ml of distilled water.
- Sodium citrate: Dissolve 10 gm of sodium carbonate in 100 ml of distilled water, then add 25 ml of distilled water.
- Magnesium trisilicate: Boil 2 gm of magnesium trisilicate with 5 ml of distilled water and 4 ml of nitric acid, then add 10 ml of distilled water, filter, and dilute the filtrate with 50 ml of distilled water.
- Ferrous gluconate: Dissolve 4 gm of ferrous gluconate with 10 ml of distilled water.
Principle of the Chloride Limit Test
- The test is based on the reaction between soluble chloride and silver nitrate in the presence of dilute nitric acid, forming silver chloride opalescence.
- Dilute nitric acid makes the solution acidic and aids silver chloride precipitation.
- Chloride impurities often come from tap water, so it is important to avoid using tap water in the limit test.
- Opalescence produced in the sample solution shows the impurity amount.
- Compare the opalescence of sample and standard solutions.
Reactions
- NaCl + AgNO3 + Dil. HNO3 → AgCl + NaNO3
- Cl- + AgNO3 + Dil. HNO3 → AgCl + NO3
Procedure for Limit Test
- Two Nessler's cylinders are required, labeled "Test solution" and "Standard solution".
Test Solution Preparation
- Add 1 ml of the prepared sample solution to the Nessler's cylinder labeled "Test solution".
- Add 10 ml of dilute nitric acid.
- Make the total volume 50 ml with distilled water.
- Add 1 ml of silver nitrate solution.
- Stir immediately and let it sit for 5 minutes.
Standard Solution Preparation
- Add 1 ml of prepared standard solution to the Nessler's cylinder labeled "Standard solution".
- Add 10 ml of dilute nitric acid.
- Make the total volume 50 ml with distilled water.
- Add 1 ml of silver nitrate solution.
- Stir immediately and let it sit for 5 minutes.
- The opalescence produced in both cylinders should be compared.
- The sample passes or fails the limit test based on whether the opalescence in the test solution is lesser or greater than the standard solution.
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