Randy Holmes-Farley
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Reef Chemistry Question of the Day [HASHTAG]#136[/HASHTAG]
From the past two questions of the day we know that oxygen molecules in air are moving about 1000 miles an hour and get only about 180 of their diameters before hitting another molecule and bouncing off in another direction.
In fact, that bouncing is why diffusion in air is so slow.
To put this in perspective, let's consider an aquarium that is 24 inches deep. When it is filled with air only, it takes almost 3 hours for an average oxygen molecule to diffuse from the tank top to the tank bottom! (we'll have more on this surprising result in later questions)
But unless you keep lizards, we are interested in water, not air. Liquid water obviously is more dense than air, and a diffusing oxygen molecule will take longer to diffuse through it because of the increased number of collisions taking place.
About how long do you think it would take an average oxygen molecule to diffuse from the tank top to the tank bottom of a 24" deep tank filled with still water?
A. 3.5 hours
B. 7 hours
C. 25 hours
D. 250 hours
E. 2,500 hours
F. 25,000 hours
Good luck!
.
From the past two questions of the day we know that oxygen molecules in air are moving about 1000 miles an hour and get only about 180 of their diameters before hitting another molecule and bouncing off in another direction.
In fact, that bouncing is why diffusion in air is so slow.
To put this in perspective, let's consider an aquarium that is 24 inches deep. When it is filled with air only, it takes almost 3 hours for an average oxygen molecule to diffuse from the tank top to the tank bottom! (we'll have more on this surprising result in later questions)
But unless you keep lizards, we are interested in water, not air. Liquid water obviously is more dense than air, and a diffusing oxygen molecule will take longer to diffuse through it because of the increased number of collisions taking place.
About how long do you think it would take an average oxygen molecule to diffuse from the tank top to the tank bottom of a 24" deep tank filled with still water?
A. 3.5 hours
B. 7 hours
C. 25 hours
D. 250 hours
E. 2,500 hours
F. 25,000 hours
Good luck!
.