Question

how much of oxygen is released from a plant

Answer 1

It will really depend on a lot of factors.

The most important one is that during the day, plants certainly perform photosynthesis for energy, using carbon dioxide and producing oxygen. But at night, when there is no light, they switch to using respiration for energy, using oxygen and producing carbon dioxide (theres a reason why plants have mitochondria, just like us).

So the important number becomes net oxygen production. This, in turn, will depend on factors such as the number of hours of sunlight or artificial light during the day.

Another very important factor is the species of plant, as well as the size of the plant.

So the short answer is that it will vary widely, and probably be somewhat less than you may have initially been thinking because of the fact plants use respiration at night.

As an aside, if you want to know how much carbon dioxide a plant has taken out of your house... well, it will be roughly equivalent to the change of the weight of your plant due to growth. (as any net carbon dioxide is converted to biological carbon and used for growth)

hypothesis time... Actually, now that I think about it, you may be able to use this to calculate the net oxygen production...

total plant growth will be proportional to net carbon dioxide absorbed plus any organic compounds absorbed from the soil. If you weighed your plant in the pot though, any gain in weight from nutrients in the soil would be in the plant and wouldnt affect this, so any increase in weight would be related solely to absorbed carbon dioxide.

Since though, the amount of oxygen produced by a plant will be somewhat proportional to the amount of carbon dioxide absorbed (with a constant that is in turn a function of species of plant, etc.). So you could potentially use the net change in weight of a plant as a measurement to calculate net oxygen production.