1. Uji Fehling - Uji Daya Mereduksi

Summary

This video script discusses a Fehling's test used to identify the reducing properties of sugars. It details the experimental setup, which involves mixing various sugar samples, including fructose, glucose, sucrose, and others, with Fehling's solutions. The key observation is the color change and formation of a red precipitate, indicating the presence of reducing sugars. Fructose, glucose, and lactose show color changes and red precipitates, while sucrose and starch remain unchanged. The script highlights the varying ability of different sugars to reduce Fehling's solution and emphasizes the role of reducing sugars in the reaction.

Takeaways

• 😀 The activity focuses on identifying reducing sugars through the Fehling test.
• 😀 The goal of the Fehling test is to demonstrate the reducing properties of sugars.
• 😀 The test involves a reaction between the sample and Fehling's solution, producing a green, yellow, orange, or red precipitate depending on the sugar type.
• 😀 The equipment used includes a test tube, volumetric pipette, pipette pump, and a beaker of water.
• 😀 The materials tested are fructose, sucrose, lactose, glucose, and starch (amilum), all at 1% concentration.
• 😀 Fehling's solutions A and B are prepared in a 1:1 ratio.
• 😀 Each sample (1 mL) is added to the test tube along with the Fehling solutions.
• 😀 The reaction mixtures are heated in water for 5-10 minutes to observe color changes and the rate of reduction.
• 😀 Fructose changes color in the first minute, while glucose and lactose show changes after the second minute, with all three forming a red-brown precipitate.
• 😀 Sucrose and starch do not show any color change or precipitate even after 10 minutes.
• 😀 The color change and precipitate formation in fructose, glucose, and lactose are due to their higher reducing sugar content, while sucrose and starch lack reducing properties.

Q & A

What is the main objective of Fehling's test in the experiment?

The main objective of Fehling's test is to demonstrate the reducing property of sugars.

What is the principle behind Fehling's test?

The principle of Fehling's test is the reaction between the solution mixture and reducing sugars, which produces a precipitate that may appear green, yellow, orange, or red, depending on the type of sugar.

What materials are used in the Fehling's test experiment?

The materials used include Fehling's solution A and B, test tubes, pipettes, a pipette pump, a beaker with water, and samples of fructose, sucrose, glucose, lactose, and starch at 1% concentration.

How should the Fehling's solutions A and B be prepared?

Fehling's solutions A and B should be mixed in a 1:1 ratio to create the testing solution.

What is the procedure for conducting Fehling's test?

The procedure involves adding 1 mL of each sample into the test tube, adding the prepared Fehling's solution, mixing the contents, and heating the mixture in hot water for 5-10 minutes.

What should be observed during the experiment?

The change in color and the formation of a precipitate should be observed. The colors may vary from green to red depending on the reducing sugar present in the sample.

What were the results for fructose, glucose, and lactose in the test?

Fructose, glucose, and lactose underwent a color change and formed a red precipitate within 1-2 minutes, indicating they are reducing sugars.

What was observed with sucrose and starch during the experiment?

Sucrose and starch did not show any color change or red precipitate even after 10 minutes, indicating that they are not reducing sugars.

Why did fructose, glucose, and lactose react quickly in the test?

Fructose, glucose, and lactose reacted quickly because they have a high content of reducing sugars, which lead to a faster reduction reaction.

Why did sucrose and starch not show any reaction in the Fehling's test?

Sucrose and starch did not show any reaction because they do not have reducing sugar properties. Therefore, they cannot reduce Fehling's solution to form a colored precipitate.