Analisis kualitatif Karbohidrat Metode Fehling. (Praktikum AKBP)

Summary

This video script outlines the Fehling's method used to detect aldehyde or ketone groups in carbohydrates by reducing metal ions. The process begins with the preparation of necessary tools and reagents, followed by the addition of specific samples (X and Y) into test tubes. Fehling's A and B solutions are added, and the mixture is heated in a water bath to observe a color change, indicating the presence of reducing sugars. The script walks through each step of the experiment with detailed instructions, ensuring proper use of equipment and reagents.

Takeaways

• 😀 The script discusses the Fehling method, which is used to detect the presence of aldehyde or ketone groups in carbohydrates that can reduce metal ions.
• 😀 The first step involves gathering the necessary tools and materials, including pipettes, test tubes, a test tube rack, and Fehling's reagent A and B.
• 😀 Fehling's reagent A is blue and Fehling's reagent B is clear, with both being used in the reaction to test the samples.
• 😀 Two samples (X and Y) are labeled and prepared for the experiment, each being treated with 1 ml of reagent.
• 😀 A pipette is used to measure and transfer 1 ml of sample to separate test tubes, with proper labeling to distinguish between sample X and Y.
• 😀 Fehling’s reagent A is added to each test tube, with a specific technique to ensure accurate measurement.
• 😀 Fehling’s reagent B is also added to the samples after using a different pipette to avoid cross-contamination between the reagents.
• 😀 The test tubes are then placed in a water bath to facilitate the reaction.
• 😀 The test tubes are left in the water bath for 5 minutes to allow the reaction to occur.
• 😀 The expected result is the formation of a red-brown color at the bottom of the test tube, indicating a positive result for the presence of aldehydes or ketones.

Q & A

What is the main objective of the Fehling's method in the practical?

The main objective of Fehling's method is to detect the presence of aldehyde or free ketone groups in carbohydrates, which can reduce metal ions.

What materials are needed for this experiment?

The materials required include a pipette (1 mL), test tubes, test tube rack, Fussball, a beaker, a tripod, a spirit lamp, wire gauze, and water bath equipment. The reagents used are Fehling's solution A (blue) and Fehling's solution B (colorless).

What are the two sample labels used in the experiment?

The two sample labels used are 'Sample X' and 'Sample Y'.

What is the role of Fehling's solution A in the experiment?

Fehling's solution A, which is blue, contains copper(II) ions that react with aldehydes and ketones. It helps in identifying the presence of reducing sugars.

Why is it important to use different pipettes for Fehling's A and B solutions?

It is important to use different pipettes for Fehling's A and B solutions to avoid contamination between the reagents, which could affect the accuracy of the experiment.

How is the sample prepared for the experiment?

For each sample, 1 mL of the sample is pipetted into separate test tubes. Each test tube is then labeled for easy identification (e.g., Sample X and Sample Y).

What happens after Fehling's A and B solutions are added to the test tubes?

After adding Fehling's A and B solutions, the test tubes are mixed and placed in a water bath. The reaction is observed over 5 minutes, where a red-brown precipitate indicates a positive result for the presence of reducing sugars.

What is the significance of the color change in the test tubes?

The formation of a red-brown precipitate at the bottom of the test tube indicates a positive result, confirming the presence of aldehyde or ketone groups that reduce the copper ions in Fehling's solution.

How long should the test tubes be left in the water bath?

The test tubes should be left in the water bath for about 5 minutes to allow the reaction to occur and to observe any color change or formation of a precipitate.

Why is a water bath used in this experiment?

A water bath is used to maintain a consistent temperature for the reaction, ensuring that the chemical process occurs properly and that the results are reliable.