How we differentiate bw citric acid and tartaric acid by identification test?
To differentiate between citric acid and tartaric acid by identification test, you can perform a simple chemical test known as the Carrez test. This test takes advantage of the difference in solubility between these two acids and allows you to visually identify each acid.
Here are the steps to conduct the Carrez test:
1. Start by dissolving the sample in distilled water. Make sure the solution is clear and free from any impurities.
2. Divide the sample solution into two equal portions, each placed in separate test tubes.
3. To the first test tube, add a small amount (around 0.1g) of potassium hexacyanoferrate(III), also known as potassium ferricyanide. Mix the solution well.
4. Add a few drops of hydrochloric acid to the test tube. If citric acid is present, you will observe the formation of a white precipitate (crystalline compound). This precipitation occurs due to the reaction between citric acid and potassium hexacyanoferrate(III), resulting in the formation of insoluble citric acid ferricyanide.
5. Now, to the second test tube, add a few drops of calcium chloride solution. Mix the solution well.
6. Next, add a few drops of sulfuric acid to the test tube. If tartaric acid is present, you will observe the formation of a white, crystalline precipitate. This precipitation occurs due to the reaction between tartaric acid and calcium chloride, forming insoluble calcium tartrate.
By following the Carrez test, you will be able to differentiate between citric acid and tartaric acid based on the formation of distinct precipitates. The white precipitate formed in the first test tube indicates the presence of citric acid, while the white precipitate formed in the second test tube indicates the presence of tartaric acid.
To differentiate between citric acid and tartaric acid, you can perform the following identification tests step-by-step:
1. Solubility Test:
- Both citric acid and tartaric acid are soluble in water. Therefore, dissolve a small amount of the acid in water and confirm complete dissolution. If the acid dissolves completely, move on to the next test.
2. Taste Test:
- Dilute solutions of both citric acid and tartaric acid have a sour taste. Dip a clean fingertip into the solution and taste it. If the taste is sour, proceed to the next test.
3. Neutralization Test:
- Both acids react with a strong base, such as sodium hydroxide (NaOH), to form a salt and water.
- Add a small amount of solid NaOH or NaOH solution to separate samples of the acids in test tubes.
- If the acid is citric acid, effervescence (bubbling or fizzing) should be observed due to the release of carbon dioxide gas.
- If the acid is tartaric acid, effervescence should not occur. Instead, a salt should form, which may be observed as a white precipitate or visible change in the solution.
4. Crystallization Test:
- Both citric acid and tartaric acid can form crystals. Prepare a concentrated solution of the acid in water by dissolving a small amount in hot water and allowing it to cool slowly.
- Citric acid crystals are colorless or white and have a crystalline or granular appearance.
- Tartaric acid crystals are colorless, odorless, and have a needle-like or prismatic shape.
By performing these identification tests step-by-step, you will be able to differentiate between citric acid and tartaric acid based on their solubility, taste, reaction with NaOH, and crystal formation.