Praktikum Kimia Amami (Angka peroksida)

Summary

This video script discusses a laboratory experiment aimed at determining the peroxide number in cooking oil, an important measure of oil oxidation. The procedure includes adding specific reagents to oil samples, followed by a titration process using sodium thiosulfate to measure the peroxide content. The experiment highlights the significance of peroxide levels, which indicate the degree of oxidation and the potential negative health effects of consuming oxidized oil. The video also outlines key steps, from preparing the sample to calculating the final peroxide number, making it a valuable resource for understanding the chemical quality of cooking oils.

Takeaways

• 😀 The focus of the experiment is to determine the peroxide number in cooking oil.
• 😀 Peroxide levels in cooking oil are crucial as they indicate oxidation, which affects oil quality and health.
• 😀 Higher peroxide numbers indicate a higher degree of oxidation and poorer oil quality.
• 😀 The presence of peroxides in oil can be caused by hydrolysis or unsaturated fatty acids reacting with oxygen.
• 😀 Oxidation can lead to the formation of free radicals, damage to blood vessels, and destruction of vitamins.
• 😀 The experimental method used to determine peroxide number is iodometric titration, using sodium thiosulfate.
• 😀 Key materials for the experiment include sodium thiosulfate, potassium iodide, acetic acid, chloroform, and the oil sample.
• 😀 The oil sample is weighed, treated with potassium iodide, and then mixed with a chloroform-acetic acid solution.
• 😀 The reaction mixture is kept in a dark place for 30 minutes to allow for oxidation, with occasional shaking.
• 😀 After 30 minutes, the sample is titrated with sodium thiosulfate until the blue color disappears, indicating completion.
• 😀 A blank titration is also performed without the oil sample to account for any reagent reaction.
• 😀 The peroxide number is calculated based on the titration volumes, and results are reported in the lab report.

Q & A

What is the main focus of this experiment?

The main focus of the experiment is to determine the peroxide number of cooking oil using iodometric titration.

Why is the peroxide number important for cooking oil?

The peroxide number indicates the level of oxidation in cooking oil. A higher peroxide number suggests the oil has undergone more oxidation, which could lead to poor quality and health risks like plaque formation and vitamin destruction.

What chemical is used to titrate the peroxide in the oil sample?

Sodium thiosulfate is used to titrate the peroxide in the oil sample.

How does oxidation affect the quality of cooking oil?

Oxidation leads to the formation of peroxides, which can degrade the oil's quality. High peroxide levels can cause the oil to become rancid, leading to potential health issues such as the formation of free radicals.

What is the method used to determine the peroxide number?

The method used is iodometry, where the peroxide in the oil is oxidized, and iodine is released, which is then titrated with sodium thiosulfate.

What are the main materials required for the experiment?

The materials required for the experiment include sodium thiosulfate (0.1 N), potassium iodide, acetic acid, chloroform, starch as an indicator, and the oil sample.

Why is the mixture stored in a dark place for 30 minutes?

The mixture is stored in a dark place to allow oxidation to occur, which is necessary for the reaction to take place before titration.

What is the purpose of using a blank test in this experiment?

The blank test helps account for the effects of reagents like sodium thiosulfate, chloroform, and acetic acid. It provides a baseline for comparison, ensuring accurate measurement of the peroxide number in the oil sample.

How do you calculate the peroxide number from the titration results?

The peroxide number is calculated using the formula: (V_sample - V_blank) × N_Na2S2O3 × 1000 / Sample mass, where V_sample is the volume of sodium thiosulfate used for the oil sample, V_blank is the volume used for the blank, and N_Na2S2O3 is the normality of the sodium thiosulfate solution.

What role does starch play in this titration process?

Starch acts as an indicator in the titration. It forms a blue complex with iodine, which disappears when all the iodine is reacted with sodium thiosulfate, indicating the endpoint of the titration.