Which is heavier, carbon monoxide, or air?

[rosalind dna]

I bought a Carbon Monoxide detector today and I was told by the engineer that Carbon Monoxide (CO) is lighter than air but then again he said the opposite as have the detector''s instructions.

I have always thought that Air is lighter than Carbon Monoxide but now I don't know for sure.

Can anyone help please?

Also link to the instructions.
http://www.sfdetection.com/pdf/Manuals/SF350/SF350%20ENGLISH%20Manual.pdf

[paul.fr]

Try this
http://www.thenakedscientists.com/forum/index.php?topic=9382.0

[turnipsock]

why not just fit two, one high one low, and then see which goes of first.

I may be to rational for this forum.

[rosalind dna]

Try this
http://www.thenakedscientists.com/forum/index.php?topic=9382.0

Thanks Paul and I have put my detector on the top of my fridge as I can't easily reach to the top of my cupboards, without a ladder.

Also I was told not to put it in the way of a draught but it's next my kitchen door and the window's the opposite side, I am very confused.

Yes Turnipsock only my kitchen is not that big.

[another_someone]

why not just fit two, one high one low, and then see which goes of first.

I may be to rational for this forum.

The problem is that unless one is doing this in a controlled situation, I would rather that neither go off at all.

[lightarrow]

I bought a Carbon Monoxide detector today and I was told by the engineer that Carbon Monoxide (CO) is lighter than air but then again he said the opposite as have the detector''s instructions.

I have always thought that Air is lighter than Carbon Monoxide but now I don't know for sure.

Can anyone help please?

CO: molar mass = 12 + 16 = 28
N₂: molar mass = 14 + 14 = 28
O₂: molar mass = 16 + 16 = 32
Dry air: ~ 4/5N₂ + 1/5 O₂: molar mass = 28*4/5 + 32*1/5 = 28.8

So CO is lighter than dry air.

Wet air can be lighter than dry air, however (if the % of water is high).

[rhade]

As air is a combination of gases itself, I'm inclined to ask "define what is meant by air."
Anyway, I live in an all electric house, so don't worry about this.

[rosalind dna]

As air is a combination of gases itself, I'm inclined to ask "define what is meant by air."
Anyway, I live in an all electric house, so don't worry about this.

Rhade, from the link that I posted in my initial thread says that
Carbon Monoxide can come from any type fuel.


Thanks Lightarrow and that is helpful, but I am not that clever with maths and equasions.

[Bored chemist]

"Carbon Monoxide can come from any type fuel. "
True, but it's a jolly clever trick to get it from electricity.

While CO is marginally lighter than air the fact that it's usually a combustion product means its usually warmer than the air round it. This means it acts like it's quite a lot lighter than air.

[rosalind dna]

"Carbon Monoxide can come from any type fuel. "
True, but it's a jolly clever trick to get it from electricity.

While CO is marginally lighter than air the fact that it's usually a combustion product means its usually warmer than the air round it. This means it acts like it's quite a lot lighter than air.

Thanks for your answer but as I had said that I am not very clever with equasions and the such-like.
Do you mean combustion like they had in the old steam trains?
Or ordinary house-hold boilers?

[MayoFlyFarmer]

Air is a mixture of many gasses.  I believe CO is actually one of the gasses that is found in small amounts in normal "air".  I've always been taught that CO detectors go down low.

[rosalind dna]

Air is a mixture of many gasses.  I believe CO is actually one of the gasses that is found in small amounts in normal "air".  I've always been taught that CO detectors go down low.

Ok but I was told to put my CO detector on my fridge as I can't reach up to the top of my cupboards easily, what do you think?

[MayoFlyFarmer]

well, that goes contrary to what i've always been told.  but i'm no expert.

[rosalind dna]

well, that goes contrary to what i've always been told.  but i'm no expert.

Contrary to what ?   The height that my CO detector should be at or that I should have been told by British Gas engineer where to  put it? Sorry for so many questions. It just want to be safe with it.

[MayoFlyFarmer]

Perhaps they have different reccomendations in the UK, but in the US, I've always read that CO detectors should be close to the floor.  That's where i always see them in people's homes too.

[rosalind dna]

Perhaps they have different reccomendations in the UK, but in the US, I've always read that CO detectors should be close to the floor.  That's where i always see them in people's homes too.

MayFlyFarmer, if I had my CO detector near the floor that's where it'd be right on the floor as in my home it's not possible.
But as you've said that it might be different in the USA as
our laws are as far as I know.

[Bored chemist]

The laws of physics are the same in the US and the UK.
Since the gas is lighter than air it will generally rise so it makes sense to install detectors near the ceiling.

[rosalind dna]

The laws of physics are the same in the US and the UK.
Since the gas is lighter than air it will generally rise so it makes sense to install detectors near the ceiling.

I know that the law of physics is the same but either side of the Atlantic but not the actual laws.
I will leave my detector were it is until someone tells me otherwise and thanks for all of your advice.

[NeilT]

The difference in density of CO and air wont make much difference to where the gas ends up. Natural diffusion and entropy will do a good job of mixing it within the room. As long as the detector is not hidden from the general flow of air in the room it should do its job.

[rosalind dna]

The difference in density of CO and air wont make much difference to where the gas ends up. Natural diffusion and entropy will do a good job of mixing it within the room. As long as the detector is not hidden from the general flow of air in the room it should do its job.

thanks NeilT and the detector can be seen easily from all angles of my small kitchen but it's on the fridge also next to the open door and the window is  the opposite end.

[rhade]

Rhade, from the link that I posted in my initial thread says that
Carbon Monoxide can come from any type fuel.
Rosalind, I believe what they meant is that CO can be produced from the generation of all types of fuel. It won't be present in the home without something actually burning in the home- but CO, and CO2, are sure as hell gonna be present at the power station, hence the need to cut our consumption to tackle climate change!

[/quote]

[rosalind dna]

Rhade, from the link that I posted in my initial thread says that
Carbon Monoxide can come from any type fuel.
Rosalind, I believe what they meant is that CO can be produced from the generation of all types of fuel. It won't be present in the home without something actually burning in the home- but CO, and CO2, are sure as hell gonna be present at the power station, hence the need to cut our consumption to tackle climate change!

[/quote]
Thanks