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?
The condensation that appeared directly above the bacteria in the Petri dishes was most likely the result of water vapor condensing. This condensation occurs when the temperature of the air in the Petri dish drops below the dew point, causing the water vapor in the air to change from a gaseous state to a liquid state.
To understand why this condensation formed, we need to consider a few factors. First, bacteria produce heat as part of their metabolic processes. This heat warms the surrounding air in the Petri dish. When this warm air comes into contact with the cooler surface of the dish, it cools down.
Next, the moisture on your hand, along with naturally occurring water vapor in the air, contains microscopic water droplets. These droplets are tiny liquid particles suspended in the air. When the warm air cools down, its capacity to hold water vapor decreases, causing the water vapor to condense into visible droplets. Since the bacteria were growing in the Petri dishes, the condensation appeared directly above them.
In summary, the condensation observed above the bacteria was most likely due to water vapor in the air coming into contact with the cooler surface of the Petri dish and subsequently condensing into visible droplets.