Dissolved Oxygen Test Procedures

The video tutorial provides a hands-on walkthrough of the AP Biology Lab 12 on dissolved oxygen. It begins with an introduction to the lab and necessary safety precautions. The instructor demonstrates how to collect and prepare a water sample, emphasizing the importance of avoiding bubbles. Chemicals are added to the sample, and the resulting reactions are observed. The tutorial concludes with a titration process to measure the dissolved oxygen content, highlighting the color change from yellow to clear as an indicator of oxygen presence.

What is the primary purpose of using the Hach dissolved oxygen test kit in the lab?

• To measure the pH level of water

• To determine the amount of dissolved oxygen in water

• To test the hardness of water

• To measure the temperature of water

What safety equipment is recommended for conducting the dissolved oxygen lab?

• Ear plugs and safety shoes

• Lab coat, goggles, and rubber gloves

• Helmet and boots

• Apron and face mask

Why is it important to avoid bubbles when collecting the water sample?

• Bubbles can affect the accuracy of dissolved oxygen measurement

• Bubbles can alter the pH level

• Bubbles can increase the water temperature

• Bubbles can change the color of the water

What is the first chemical added to the water sample in the dissolved oxygen test?

• Potassium iodide

• Manganous sulfate

• Sulfamic acid

• Sodium thiosulfate

What color change indicates the presence of oxygen in the water sample?

• Green

• Brown

• Red

• Blue

What is the role of sulfamic acid in the dissolved oxygen test?

• To add more oxygen to the water

• To remove the precipitate and turn the solution yellow

• To measure the pH level

• To increase the water temperature

What is the purpose of the titration process in this lab?

• To add more chemicals to the solution

• To increase the temperature of the solution

• To determine the amount of dissolved oxygen

• To measure the pH level of the solution

Which chemical is used in the titration process to turn the solution clear?

• Sodium thiosulfate

• Sulfamic acid

• Manganous sulfate

• Potassium iodide

How many drops of sodium thiosulfate were needed to turn the solution from yellow to clear?

• 12 drops

• 10 drops

• 7 drops

• 5 drops

What does a clear solution indicate at the end of the titration process?

• The absence of oxygen

• The solution is basic

• The presence of oxygen

• The solution is acidic