What is Chemical oxygen demand | analysis of high [COD] sample | Dilution method

Summary

In this engaging chemistry video, Sanjay Dutt demonstrates the procedure for measuring Chemical Oxygen Demand (COD) in a sample. The process involves preparing solutions, incubating the samples, and conducting a titration with Sodium Thiosulfate to observe color changes. Viewers learn about the importance of precise measurements and calculations, culminating in the determination of the COD value. The tutorial is designed for those interested in chemistry, offering practical insights and encouraging questions for further understanding.

Takeaways

• 🎓 The video is presented by Sanjay Dutt, focusing on Chemical Oxygen Demand (COD) analysis.
• 🧪 The procedure involves preparing samples using 0.5 Normal Protection Dichromate Solution and mercuric sulfate.
• 💧 A key step is adding 15ml of concentrated sulfuric acid to both blank and sample solutions.
• ⏳ The samples must be shaken and left to react for 24 hours before further processing.
• 🌡️ The samples are then diluted with 10ml of distilled water for the COD analysis.
• 🌀 Proper mixing of the samples is crucial for accurate results, and rinsing equipment helps prevent contamination.
• 🔍 The color change during the addition of acid is monitored, indicating the progress of the reaction.
• 🔥 The samples are heated at 140-150°C for 2 hours to facilitate digestion.
• 📊 Titration is performed with a pH indicator, and a brick-red color marks the endpoint.
• 📈 The final COD result is calculated using a specific formula, with the sample yielding 1,088,000 mg/L.

Q & A

What is the purpose of the 0.5 normal protection dichromate solution in the experiment?

The 0.5 normal protection dichromate solution is used to measure the Chemical Oxygen Demand (COD) of the samples.

What steps should be taken before adding samples to ensure accurate results?

Before adding samples, it is important to clean the apparatus thoroughly and rinse it multiple times to avoid contamination.

How much concentrated sulfuric acid is added to each sample?

15 ml of concentrated sulfuric acid is added to each sample in the experiment.

Why is the blank sample important in this experiment?

The blank sample serves as a reference point for comparison, allowing for accurate measurement of the COD in the test sample.

What color change indicates that a reaction has occurred in the samples?

A green color change indicates that the reaction has occurred after the addition of the blood sample to the mixture.

What is the recommended temperature for digesting the samples?

The samples should be digested at a temperature of 140-150 degrees Celsius for two hours.

How is the endpoint of the titration determined?

The endpoint of the titration is determined by observing a color change to brick red after adding the indicator to the sample.

What calculation is used to determine the COD from the titration results?

The COD is calculated using the formula: COD = (0.5 ml * 280) / Volume of sample.

What should viewers do if they have questions about the experiment?

Viewers are encouraged to ask questions in the comments section of the video or contact the presenter on Instagram for further clarification.

What is the significance of proper sample dilution in this experiment?

Proper sample dilution is crucial for ensuring accurate measurements and preventing the failure of the experiment due to overly concentrated samples.