I was growing some bacteria in Petri dishes that I got from wiping my hand with a q-tip. Condensation appeared directly above the bacteria when they got somewhat large. Was this H20 or something else? And why did it form?
Humm The products of ellular respiration are water and carbon dioxide. I wonder if this might be the source of the water?
But if the water came from cellular respiration, why would it be above the bacteria? Wouldn't it just be next to it or something? (The bacteria were in Petri dishes sitting right side up, the droplets appeared on the inside of the lids)
It appeared above because the outside temperature was low enough to condense the water vapor being given off from the bacteria.
The condensation that appeared above the bacteria in your Petri dishes could indeed be water vapor. Let's break it down step by step to understand how this condensation formed.
1. Source of water: As you mentioned, the byproduct of cellular respiration is water. In the case of bacteria, they undergo cellular respiration to produce energy, releasing water vapor as a result.
2. Distribution of water vapor: The water vapor generated from cellular respiration is a gas and can diffuse to the surrounding air. Since you observed the condensation on the inside of the lids, it suggests that the water vapor was able to move away from the bacteria and disperse throughout the container.
3. Low temperatures: The condensation occurred above the bacteria, rather than next to it, because the outside temperature was low enough for the water vapor to cool down and condense into liquid droplets. Since the lids of the Petri dishes were on top, they were in direct contact with the cooler air, causing the water vapor to condense on the inside surface of the lids.
To summarize, the condensation forming above the bacteria in the Petri dishes was water vapor that was released as a byproduct of cellular respiration. It then condensed on the inside of the lids due to the lower temperature outside the dish causing the water vapor to cool and turn into liquid droplets.