Well, the way you're using it IS a bunch of hokey. You've calculated
molar density, not mass density. That's equivalent to saying 100
bowling balls takes up more space than 100 baseballs, since a 'mole'
is just a fixed number of atoms (somewhat more than a 'sh*tload'). It
says nothing about which is 'heavier'. You're better off just
ignoring molar density (as the previous poster did ) since, as you
note, they're all pretty close, and just going with the mass density.
CO2 is denser than 'air', and CO is slightly lighter.
100 bowling balls do take up more space than 100 baseballs, and the size
of the molecules is something the Van der Waals equation takes into
account that the Ideal Gas equation does not. (at STP the variation is
not very significant, but if you use the ideal gas equation, obviously
you get the same answer for every compound). [for people who don't
remember their chemistry a mole is Avogadro's number of particles ~= 6.02
If you take the molar density and multiply by the molecular weight, you
get the mass density.
Assuming the numbers are right, oxygen has more mass density than carbon
monoxide (but slightly less particle density). For purposes of
asphixation, the CO vs O2 comparison is what matters.
I still can't work out how mass density is relevant when talking about
gases or how adding atomic weights can give a correct indication of
density or buoyancy. It would be akin to saying water floats on oil
(obviously it doesn't), because water (1 + 1 + 16 = 18) is lighter than
oil (say minimum of 2 H and 2 C = 26). To me it makes more sense (when
talking about gases at least) to talk about particle density, but I'm not
convinced particle density is the solution, either.
Not really... O2 and N2 don't separate out - they form, effectively, a
'solution', so the density of 02 is not really relevant. It's the
density of 'air' which matters, which is between the density of air
and nitrogen (and closer to nitrogen).
Because mass density, coupled with gravity, is what causes bouyancy.
Because for most gases (at fixed temperature and pressure), the molar
volume (molar density) is roughly constant, thus the molecular weight
is a good indicator of the mass density, which determines bouyancy.
If we say that a mole of any gas occupies roughly 24 liters at STP,
and a mole of gas weighs it's molecular weight in grams, then the
density of any gas is proportional to it's molecular weight. The
density of CO2 is thus about 44 grams per 24 liters.
No, gases and liquids are vastly different phases. The molar volume
of most gases (at STP) is roughly the same; the molar volume of
liquids can be orders of magnitude in difference.
Nope, not at all. Gravity doesn't care at all about particles, it
only cares about mass...
This property can come in very handy, as long as you know a few
key atomic weights. Say, for instance, that you're stuck in a boring
class or lecture. No problem. Whip out your pencil and notepad and
calculate how much H2 it would take to float your neighbor's cat into
the stratosphere. Next, calculate how much He to do the same thing.
Look up at the lecturer from time to time, appearing thoughtful. He or
she will be impressed that you're taking more notes than any one else
in the room.
The above is a purely hypothetical scenario. <g>
As I mentioned in my previous post, I think those volume figures are
a little off.
According to my handy-dandy Pocket Ref, here are the densities (@
O2 1.4290 g/L
N2 1.2506 g/L
CO 1.2500 g/L
CO2 1.9770 g/L
Air 1.2928 g/L
Just as a sanity check, I multiplied each one of those figures by
22.4 to make sure that the product was close to the molecular mass
Ha, thanks, but mine were way off. This is why I am not a chemist (or
mathematician). The correct equation is probably: v^3 - (b + RT) v^2 + a
V - ab = 0 (forgot to multiply RT by v^2 last time)
CO 1.168 g/L at 20C, 1 atm
CO 1.253 g/L at STP (using 28 for mass)
Close enough to the value you reported.
Calculations for other compounds are an exercise left to the reader
I think there's something wrong with those numbers. 1 mole of
(ideal) gas occupies 22.4 L @ STP. Your numbers should vary slightly.
Kelly's already done a bang-up job of explaining why you need to
bring mass back into the picture.
Um. Hate to be practical and everything here, but if you're forcing
a gas into the gopher hole, the density doesn't matter; it's not going
there by gravity, it's going there by pressure. You could force
helium down there and it'd go down rather than up, density and
molecular mass notwithstanding.
But isn't it true that there exists some "heavy" gas that will tend to
collect at a lowest elevation? I don't remember exactly what carbon
monoxide does, but it's possible that I've also heard that it sinks
(compared to say something like helium which obviously wants to rise).
The question is whether CO is one of those gases.
Is not...Oxygen (O2, molecular wt 32) will settle slowly...Carbon
Dioxide (CO2, molecular wt 44) settles fairly well...Propane (C3H8,
also molecular wt 44), settles well enough to cause major problems if
a leak occurs.
country doc in louisiana
(no fancy sayings right now)
actually, carbon monoxide, at mol wt 28 (same as N2) is slightly
lighter than air (avg formula wt approx 30).
and there have been a number of documented human survivors from failed
CO suicide attempts because the engines shut down before the air in
the garage became lethal.
and cigarette smokers frequently tolerate levels of carboxy hemoglobin
that would debilitate folks who didn't smoke.
country doc in louisiana
(no fancy sayings right now)
Animal Control here WILL NOT deal with anything but dogs and cats and the
occasional potbelly pig. Raccoons are *wildlife* and therefore non-domestic
and not their problem. If you have an injured one, the state wildlife guys
will direct you to a vet and foster parent, but they don't deal with them
either unless they're possibly rabid, and since that's not happened since
sometime in the 70's, you just get told to call a pest control firm who'll
charge you big bucks and still not solve your problem.
If the original poster and his child are too stupid to install an electric
wire like was recommended, then let him deal with no fish in the fish ponds
and no veggies in the garden and several ER bites from trying to trap them.
Evolution in action. He'll either learn what futility is, or he'll actually
educate himself on electric fences and not subscribe to ignorant hysteria.
I'll bet he's even touched his tongue to a battery as a child, but somehow
he thinks that should have electrocuted him.
Hmm. They were more than happy to come over to my house to remove a raccoon
that was wandering around the yard in broad daylight. Is it possible that
animal control departments are different from one place to another? Would it
hurt to call and ask?
I'm pretty sure it takes more than 9v to scare off a racoon. So how much
voltage would you use that would do the job but not hurt the child? I know
you can die from as little as 50v. Even less if you got imaginative.
Don't let your kids wear wool socks on a low humidity day...imagine what
would happen if they discovered they can shuffle around the house and zap
each other with a few thousand volts. A typical static electricity shock is
about 2000 - 4000 volts.
Of course a amperage involved is so low, that aside from the surprise, no
damage is done. Ever taken a weak 9v battery and tapped it against your
tongue? A fresh battery hurts a little, but a weak one gives a little
A consumer grade electric fence is harmless, it will give a mild shock, but
nothing dangerous. I couldn't find the specifications online, so
guestimating, if an electric fence transformer draws 120v A/C @ 1 amp, the
output would be 4000 v A/C at .03 amp.
That's just a mild shocker, pretty safe..if it was D/C on the otherhand is a
<A consumer grade electric fence is harmless, it will give a mild shock, but
<nothing dangerous. I couldn't find the specifications online, so
<guestimating, if an electric fence transformer draws 120v A/C @ 1 amp, the
<output would be 4000 v A/C at .03 amp.
<That's just a mild shocker, pretty safe..if it was D/C on the otherhand is a
Doesn't matter whether it's A/C or D/C.
Here's a reference:
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