AP Biology Lab 12: Dissolved Oxygen

The video tutorial demonstrates a hands-on walkthrough of measuring dissolved oxygen using the HAWK test kit. It covers safety precautions, collecting and preparing a water sample, adding chemicals, observing reactions, and performing a titration. The process involves using various chemicals to detect oxygen presence and measure its concentration through color changes and titration.

What is the primary purpose of using a lab coat, goggles, and rubber gloves in the dissolved oxygen experiment?

• To protect against chemical spills

• To look professional

• To keep warm

• To avoid getting wet

Why is it important to avoid bubbles when pouring the water sample into the bottle?

• Bubbles can cause the bottle to overflow

• Bubbles can alter the dissolved oxygen measurement

• Bubbles can make the water cloudy

• Bubbles can increase the water temperature

What indicates the presence of oxygen in the water sample after adding the first set of chemicals?

• A green color

• A red color

• A blue color

• A brownish color

What is the role of sulfamic acid in the experiment?

• To increase the water temperature

• To remove the precipitate and turn the solution yellow

• To add more oxygen to the water

• To neutralize the water sample

What is the purpose of the titration step in the dissolved oxygen experiment?

• To change the color of the solution

• To add more chemicals to the solution

• To determine the exact amount of dissolved oxygen

• To measure the water temperature

How do you know when to stop adding sodium thiosulfate during the titration?

• When the solution turns blue

• When the solution becomes cloudy

• When the solution turns red

• When the solution becomes clear

What is the significance of the yellow color in the titration process?

• It shows the presence of oxygen

• It indicates the presence of nitrogen

• It suggests the solution is too basic

• It means the solution is too acidic