What to do next:
Rub a little Vaseline on the tip of the vials to make it easier to complete the next step.
Attach a vial to each syringe.
What will happen:
What will happen now is that when the bacteria in the water is breathing, the bubble will go up the vial, showing how many mLs of oxygen the bacteria are consuming. This is relevant because the more bacteria, the more oxygen consumed, so for example, the tap water consumed more oxygen, that means there is more bacteria in the tap water than any other sample of water.
We needed to soak the cotton balls in Potassium Hydroxide, because Potassium Hydroxide will absorb the Carbon Dioxide in the air, making it a healthier environment for the bacteria to thrive in.
Now, we need to record every 5 minutes how far the bubble has gone up the vial.
Then we find the average of oxygen consumed per minute using the calculator.