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Non Life Sciences => Chemistry => Topic started by: scientizscht on 03/11/2019 08:54:05

Title: What is the rate of oxygen diffusion from the atmosphere to a glass of water?
Post by: scientizscht on 03/11/2019 08:54:05
Hello

When you have a glass pod with water and a goldfish, the fish consumes oxygen in the water at a specific rate.

This should be smaller than the rate that oxygen enters the water in the pod from the atmosphere.

What is that rate?

Thanks
Title: Re: What is the rate of oxygen diffusion from the atmosphere to a glass of water?
Post by: Bored chemist on 03/11/2019 09:41:05
The oxygen in the water will, at least in part be consumed by the fish and some by microorganisms.
It will be supplied by plants and by diffusion.

On the whole the rate of diffusion of oxygen into the water will not be more than the requirements of the fish and  other occupants of the bowl- it will be exactly the same.

To a rough approximation, the rate of oxygen delivery will be the same as that which would be required to burn the fish food.
That might be the easiest thing to estimate.
Title: Re: What is the rate of oxygen diffusion from the atmosphere to a glass of water?
Post by: scientizscht on 03/11/2019 12:34:14
Quote from: Bored chemist on 03/11/2019 09:41:05
The oxygen in the water will, at least in part be consumed by the fish and some by microorganisms.
It will be supplied by plants and by diffusion.

On the whole the rate of diffusion of oxygen into the water will not be more than the requirements of the fish and  other occupants of the bowl- it will be exactly the same.

To a rough approximation, the rate of oxygen delivery will be the same as that which would be required to burn the fish food.
That might be the easiest thing to estimate.

Where did you see the plants?

It is interesting that oxygen takes hours to travel 10cm in water, so how doesn't the fish consume the whole oxygen in the pod much faster?
Title: Re: What is the rate of oxygen diffusion from the atmosphere to a glass of water?
Post by: Bored chemist on 03/11/2019 18:43:16
Quote from: scientizscht on 03/11/2019 12:34:14
Where did you see the plants?
In any fish bowl set up anything like properly.
Title: Re: What is the rate of oxygen diffusion from the atmosphere to a glass of water?
Post by: evan_au on 03/11/2019 20:23:22
In any thriving fishtank, I also see a stream of bubbles floating from the bottom to the top, driven by a pump.

Fine bubbles greatly increase the surface area in contact between the air and water, increasing oxygen delivery and carbon dioxide extraction.
Title: Re: What is the rate of oxygen diffusion from the atmosphere to a glass of water?
Post by: chiralSPO on 03/11/2019 20:28:01
Quote from: evan_au on 03/11/2019 20:23:22
In any thriving fishtank, I also see a stream of bubbles floating from the bottom to the top, driven by a pump.

Fine bubbles greatly increase the surface area in contact between the air and water, increasing oxygen delivery and carbon dioxide extraction.
And the bubbles agitate the water, causing mixing, so diffusion doesn't limit oxygen distribution!
Title: Re: What is the rate of oxygen diffusion from the atmosphere to a glass of water?
Post by: scientizscht on 04/11/2019 08:19:06
There are bowls without oxygen pumps.
Title: Re: What is the rate of oxygen diffusion from the atmosphere to a glass of water?
Post by: Bored chemist on 04/11/2019 08:39:09
Quote from: scientizscht on 04/11/2019 08:19:06
There are bowls without oxygen pumps.
https://www.rspca.org.uk/adviceandwelfare/pets/fish/environment