Is carbon monoxide heavier or lighter than air?

Question

I just got a battery operated detector and want to be sure I place at the right height to be most effective, since CO kills people.

Answer 1

Air is a mixture (not combination of basically 2 gases: oxigen (O2)and nitrogen (N) in its molecular form. Carbon monoxide (CO) is a molecule made of 1 carbon atom (6) + 1 oxygen atom (8) = 14. Therefore, CO is heavier than N, which molecular weight is just 7, but slightly lighter than the O2 molecule, that wheighs 16.

In my opinion, a CO detector could be placed anywhere at the height of adult human nostrils, since it's a substance easily mixable with air.

Answer 2

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Taking the average composition of air(78% nitrogen and 21% oxygen) you get an average weight for air of about 28 amu's. Carbon monoxide has a weight of 30 amu's so it's slightly heavier. Looking at air differently carbon monoxide is heavier than nitrogen gas but lighter than oxygen gas.

Answer 3

Answer
Look at the main consituents of air:

1. Nitrogen (N2) has a molecular weight of 28 (14x2)

2. Oxygen (O2) has a molecular weight of 32 (16x2)

3. Water (H2O) has a molecular weight of 18 (2x1 + 16)

4. Carbon dioxide(CO2)has a molecular weight of 44 (12 + 2x32)

Carbon Monoxide(CO)has a molecular weight of 28 (12+16)

So compared to the main constituents CO is lighter than O2 and CO2 and heavier than H2O. It is the same as N2. Since however, the nitrogen is equal and makes up almost 80% of the air, CO basically stays where you release it. If you had a CO gun, it would really go where you point it.

Now since the O2 is heavier than CO and the second largest % in air, the CO will spread up as compared to the O2. My guess is that this takes a long period of time, without outside forces. So in a closed situation, with enough time, and no other air movement, the CO will drift up, not to all be at the top, just slightly more of it. Same with O2, since more will be low, in a fire that is the place to be (also the smoke goes up also).

Take CO2 for example. It is the heaviest of them all, but in a regular room, it would be almost impossible to find more CO2 on the floor, than on the ceiling. There is just too much air movement that keeps things mixed up.

Now take CO coming off a poorly ventillated wood stove. That CO is lighter than O2 by weight, but remember, it is also hot compared to the N2 in the room. Hot gas is always lighter than cold, so CO in this case would be lighter than the N2, so it would go up due to the temperature difference.
By the same token, if you released cold CO, it would go down.

Not a simple answer, but if you only had the choice of up or down, the CO is lighter than O2, and the same as N2, so it would go up. If you throw other variables such as temperature in, you can get different answers.

Answer 4

The two are really close, almost equal. Nitrogen has an atomic weight of 14 so N2 is 28 amus per molecule. CO has aweight of 28 amus, so the other heavier components of air make CO lighter, just slightly.

Answer 5

The molecular weight of CO is 12+16=28. If you take the average molecular weight of air with N2[28],O2[16],...air turns out to be slightly heavier.

Answer 6

It's lighter. C has 12 O has 16, co 28, N2 (28) and O2 (32) mixture is slightly heavier but see
http://www.newton.dep.anl.gov/askasci/chem03/chem03364.htm

Answer 7

Carbon Monoxide is lighter than air, but not a great deal lighter.

You should follow the instructions that came with your detector - as it will advise you where best to place it.

Answer 8

Under ordinary circumstances it is less dense, lighter, than air. CO detectors can be placed near the ceiling or near the floor as CO is very close to the same density as air.

Answer 9

Hi. It is lighter than air. : http://www.answers.com/main/ntquery?s=carbon%20monoxide&gwp=16

Answer 10

Heavier.