If all oxygen in atmosphere is converted to CO2, would the atmosphere be at higher pressure? What pr
Submitted : 20180614 05:47:35 Popularity:
Tags: converted atmosphere oxygen pressure higher
Yes. Why? You would basically be adding carbon from the ground to the air if this were to happen. C+O2=CO2.
The amount of O2 in the air is about 20%
Yes. Why? You would basically be adding carbon from the ground to the air if this were to happen. C+O2=CO2.
The amount of O2 in the air is about 20% by volume, or about 23% of the mass of the air (O2 is a little more dense than N2 so the mass percent of O2 in air is higher than its volume percent). We can call this about 0.3 kg per cubic meter at ground surface (air has a density of about 1.3 kg per cubic meter at ground surface, depending on temperature mostly). Converting all that O2 to CO2 (adding C from the ground) would create a mass of 44/32 * 0.3 kg in that cubic meter of air, or roughly 0.4 kg of CO2 after the change (increase of about 35%).
Of course, there is a change in volume when you add mass, but conversion of O2 to CO2 has only a small effect on total volume (CO2 is about 30% more dense than O2, so mass is added without much changing volume). The net effect is that the cubic meter of air that we started with would now have pretty close to all of that added carbon in the same volume of air. The 1.25 kg of air at the start would now be about 1.35 kg of air in the same cubic meter, or let's round it off to an increase in 10% by mass.
Pressure is basically the total weight of all the air above, and that would increase by about 10%, so the pressure would as well. Naturally, increasing the pressure would affect the density we used to come to this, so the net effect would be a little less.
This is all backoftheenvelope calculation so only order of magnitude estimate. Somewhere about midway between 5 and 10 % would be what would happen. Gets a bit complicated if you take pressure change effects on density into account and the effects of temperature change due to increase in pressure (adiabatic compression), both of which I completely ignored.
Assuming no carbon was added to the atmosphere, the overall pressure would not change at all.
If carbon was added, the total mass of the atmosphere would increase, thus increasing the pressure at ground level.
Rule of thumb:
There is approx 4 molecules of N₂ for 1 of O₂ (the distribution is given in volume, not in mass. And under the same pressure, volume is proportional to the number of molecules)
So, 5 moles of air are, roughly, 4 of N₂ and 1 of O₂. That is 4*(28)+32 grams per 5 moles = 144 grams per 5 moles (the "per 5 moles" part is useless as long as the second part of the calculation is done with the same unit. So, no need to divide by 5, or multiply by the total number of moles)
If instead we had 4 N₂ and 1 CO₂, that would be 4*28+44=156 instead of 144.
So the increase of mass would be by the ratio 156/144.
Increase of the pressure would be in the same proportion.
So 108 kPa instead of 100 kPa
Or, 16 PSI instead of 15
So, yes, the pressure would be higher; Not very significantly higher though. You experience more variation of pressure than that without knowing it.
108kPa has already been recorded multiple time by meteorological stations (and also 870 kPa near typhoons)
And it is even worse if you fly or climb a mountain. For example Ecuador's capital, Quito, has a pressure more than 30% less than average. So the 8% of variation are not a lot.
If all O₂ were replaced by CO₂, I would worry far more about how I can breathe than about the slightly highest pressure.
But all that being said, yes, pressure depends on the composition of the atmosphere. If you replace some gas of the atmosphere by heavier gas, the pressure increases, indeed.
The beauty of CO2 is 2 oxygen. :) More air! LMAO
You bet yah. CO2 atomic weight is heavier than O2 because of the carbon atom, so the density factor becomes greater causing more atmospheric pressure assuming space was made up of another element than CO2 lets say hydrogen. Then the atmospheric pressure would be about three times higher than O2 and CO2 mixtures, assuming if we humans could breathe it.


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