Demonstration, Free Sulfur Dioxide, Aeration-Oxidation Method

Summary

In this instructional video, viewers are guided through the process of measuring sulfur dioxide (SO₂) in wine using a detailed setup with glassware, chemicals, and precise techniques. The presenter emphasizes safety measures, including wearing goggles and gloves while handling strong acids. Key steps include preparing the wine sample, adding indicators, and conducting a titration with NaOH to determine the free sulfur content. The final calculation reveals how much SO₂ is present in the wine, providing essential insights into wine quality. This practical demonstration combines chemistry with a hands-on approach to wine analysis.

Takeaways

• 🔍 Takeaway 1: The experiment focuses on measuring the sulfur dioxide (SO2) content in wine using a specific setup.
• 💡 Takeaway 2: The setup includes an air pump, glassware, phosphoric acid, sodium hydroxide (NaOH), and a SO2 indicator.
• 🧪 Takeaway 3: Safety precautions are essential, including wearing safety goggles and gloves when handling strong acids.
• 🍷 Takeaway 4: The process begins by measuring 20 mL of white wine and adding hydrogen peroxide and a SO2 indicator.
• ⚗️ Takeaway 5: The solution turns green after adding the SO2 indicator, indicating the presence of SO2.
• ⏱️ Takeaway 6: After adding phosphoric acid, the reaction must be quick as it stops immediately upon addition.
• 🚀 Takeaway 7: The vacuum pump is turned on for 10 minutes to allow the reaction to proceed.
• 💧 Takeaway 8: A burette is filled with 0.1 NaOH and purged to remove any air bubbles before titration.
• 🌈 Takeaway 9: Titration is performed to change the solution's color back to green, indicating the end point.
• 📊 Takeaway 10: The amount of NaOH used in the titration helps calculate the free sulfur content in wine, with a conversion factor of 16 parts per million per mL.

Q & A

What is the main objective of the experiment?

The main objective of the experiment is to measure the amount of free sulfur dioxide (SO₂) in a sample of wine.

What equipment is used for measuring SO₂ in the wine?

The equipment includes the iPhone 5000 setup, an air pump, glassware (glass bulb with stopper, beakers), 25% phosphoric acid, 0.01 NaOH solution, SO₂ indicator, a 20 mL pipette, and a buret.

What safety precautions are mentioned in the script?

The script mentions wearing safety goggles and gloves due to the use of strong acids during the experiment.

How much white wine is required for the experiment?

The experiment requires 20 mL of white wine.

What is the purpose of adding hydrogen peroxide to the wine sample?

Hydrogen peroxide is added to the wine sample to facilitate the reaction for measuring free sulfur dioxide.

What color change occurs after adding the SO₂ indicator to the wine?

After adding the SO₂ indicator, the solution should turn green.

What happens when phosphoric acid is added to the wine?

As soon as phosphoric acid is added to the wine, the reaction stops, so it is crucial to proceed quickly after this step.

How is the titration process conducted in the experiment?

The titration process involves adding 0.1 NaOH to the purple solution until it turns green, with the goal of stabilizing the green color for about 10 seconds.

How is the concentration of free sulfur in the wine calculated?

The concentration of free sulfur is calculated by multiplying the volume of NaOH used (after subtracting the starting point) by 16. For example, if 1.0 mL of NaOH was used, the free sulfur concentration would be 16 ppm.

What should be done with the used samples and equipment after the experiment?

All used samples should be disposed of properly, and the glassware should be cleaned with distilled water.