Experimentation with Gasses: CO2 Produced or Not?

[zking786]

This is probably a very elementary question, but I was wondering how one could (relatively inexpensively and with everyday items) test for the presence of carbon dioxide in a chamber. More importantly, is there a way I could quantify the amount of CO2 in the chamber?

 

I'm doing an experiment and want to see if CO2 is a byproduct, so I should be able to tell whether the concentration of CO2 has increased by the end of the experiment, so the pressure or volume of CO2 isn't necessary.

[silkworm]

What do you have to work with (home kitchen/Wal-Mart, actual scientific equipment)?

 

What type of chamber are we talking about?

 

What type of process are we talking about?

[aj47]

Bubble through lime water which turns white in the presense of CO2

[zking786]

Interesting, why does lime water turn white in the presence of CO2?

 

Also, to answer silkworm's question, I don't have many reagents at home. The process is, I'm melting a carbon rod in water by passing lots of current through it. The result is H2 and I'm not sure if CO2 is a byproduct, since I don't think O2 is and there doesn't seem to be any solid precipitation.

[xeluc]

the precipitate is caused by the creation of Calcium Carbonate which is insoluble at first.

[ecoli]

The other option is tag the Carbon with a radioactive isotope... I think a chemical test might be better.

[RyanJ]

Use an ignited splint, if there is a high concentration of Carbon Dioxide it will be extinguished

 

Ecoli, I'd like too see a home chemist do that

 

Cheere,

 

Ryan Jones

[ecoli]

Use an ignited splint, if there is a high concentration of Carbon Dioxide it will be extinguished

 

Unfortunately, you can't quantify your data that way.

 

Ecoli, I'd like too see a home chemist do that.

 

no problem

[insane_alien]

what sort of pressures are you using. i was under the impression that carbon doesn't have a liquid state achievable with current technology since it is solid all the way up to ~3000K by which point all the water would have boiled off

[ecoli]

insane_alien... he's trying to do it at home, 1 atm. at room temp.

[jdurg]

Unfortunately' date=' you can't quantify your data that way.

 

 

 

no problem [/quote']

 

 

In addition, there are many gases that will extinguish a flame not just CO2.

[RyanJ]

Unfortunately, you can't quantify your data that way.

 

Good point and even if you could it would not be a very accurate method anyway

 

Cheers,

 

Ryan Jones

[zking786]

The temperature is supposed to be very high, causing Carbon to sublime (I think forming CO2, but I'm not sure). As stated, the temperature of the water in the container is room temp and the pressure is 1 ATM.

 

For more details on my experimentation see this thread:

http://www.scienceforums.net/forums/showthread.php?t=17238

[YT2095]

when carbon sublimes, it simply reforms back into carbon again, it`ll not produce CO or CO2.

[zking786]

Interesting, so either I would get carbon or an alotrope of carbon in the mixture--not CO2 or CO. I can't detect anything in the container after the process is complete, though.

 

Also, what temperature do you think Carbon (or this alotrope used for welding) would sublime at?

[insane_alien]

3800 K [or 3527°C (6381°F)]

[zking786]

I guess it could be that hot? I'd need to do some thermodynamics to find out. Too bad I don't know anything about heat transfer and don't have the apparatus at hand. But, it is clear that the carbon is disappearing from the rod. I didn't notice any carbon residue in the container, wonder what's happening?

[jdurg]

I would guess that the carbon is disintegrating and immediately reacting with the oxygen produced to form CO2. With a very large surface area, it's quite possible that this is what is happening.

[zking786]

That's what I thought, but YT2095 said it'll only sublime and then reform Carbon again--it won't combine with anything else.

 

Any ideas?

[YT2095]

The temperature is supposed to be very high, causing Carbon to sublime (I think forming CO2, but I'm not sure).

 

my point is that sublimation is not reaction, it only involves a phase change. to make CO2 requires a Reaction (specificaly with Oxygen).

they`re 2 different words.

[jdurg]

That's what I thought' date=' but YT2095 said it'll only sublime and then reform Carbon again--it won't combine with anything else.

 

Any ideas?[/quote']

 

You appear to be mis-interpreting what YT is saying. You had originally said that the carbon would sublime thus forming CO2. That's not the case. YT was saying that sublimation is a phase change. When ice melts, it forms liquid H2O not some other compound. Your original post made it seem as if the carbon sublimes and upon the phase change becomes another compound. That's not possible.

 

What CAN happen is that the carbon sublimes and at the elevated temperature and high surface area it then reacts with oxygen to form CO2.

[zking786]

That makes sense, sublimation is a phase change directly to gas (from solid in this case). Question is, at high temperature will the carbon bond to the disassociated oxygen?

 

I guess I might have to pass the gas through lime water to find out.

[jdurg]

That would be your best bet and would also provide pretty conclusive proof that you are generating CO2 gas.