a Fuel cell maybe?

[YT2095]

I`ve just discovered something Very strange.

 

I`de set up my Hoffman Voltameter a while back, and after filling both sides H2 and O2 respectively, I put it to one side and thought no more of it.

but Slowly the levels were starting to drop unil it had swung towards Negative pressure!? a Vacuum of sorts.

I suspected that it was acting as a type of barometer, but I thought I`de check the carbon electrodes for Voltage anyway (I have no idea what made me think of that), and sure enough there was Voltage present:eek:

 

2 identical electrodes in dilute Sulfuric acid with O2 in one column and H2 in the other.

 

so I refilled them to Positive pressure again and I`m getting 14.8ma at .83v.

I now have them under a constant load (a small moving coil ammeter), it would seem that the O2 is consumed much faster than the H2 also?

 

has anyone got an explaination for this?

[Wookiee]

Hmm...

 

I really have no authority to say or know whats happening but...

It would seem as though the oxygen is playing games.

1. I could see it not being pure oxygen(maybe CO2 is being produced along with O2 and therefor producing less O2 for the same H2)

2. Its disolving in the water a lot?

3. Maybe the oxygen is reacting with the carbon during the "fuel cell" operation?

 

Personally I think it has something to do with the carbon electrodes and oxygen. I don't really think the cause is the hydrogen. But I could be wrong.

 

Just my thoughts...

-Randy

[YT2095]

well it turns out from a few experiments I`ve conducted Further to this, that the Gas liberated at the Anode was never Pure O2 anyway (that would explain the lame result with the glowing splint test).

I evacuated the "O2" Anode column and replaced it with pure O2 from a gas bottle and then left it overnight.

Non of the O2 was taken, the level remained Constant.

I also shorted the outputs just in case it was some sort of Surface charge on the electrodes.

 

this morning I dumped the O2 out, evacuated the column and put in CO2 gas from a bottle, THAT is now being absorbed/used at a rate of about 1ml/hour and the voltage has increased again!?

 

the H2 has gone down just over half a ml in 28 hours.

 

it also goes some way to explain why I wasn`t getting the 1:2 ratio during electrolysis, I`de have to dump the H2 side 4 to 5 times to fill the Anode side.

 

so, it would seem at Face value that CO2 is being used as a "Fuel" in this cell.

which makes no sense at all, as CO2 is a Waste Product isn`t it?

 

I can`t really think of a reaction formula nevermind a Mechanism!

 

CO2 + H2 = H2O and CO maybe?

CO2 + 2H2 = 2H2O and C?

 

but I`m fairly sure that these would Require Energy and not Give energy!???? certainly not Electrical anyway.

[Wookiee]

weird...

 

Are you sure its still Hydrogen after running it as a "fuel cell"? It could possibly be just replacing the H2 with say CO2 or CO. I wouldn't know why or how.

 

Maybe its creating CO from CO2 and using 2H2 and O2(from CO2) to create 2H2O...

CO2 + H2---> CO + H20

 

It could possibly make sense.. Aslong as the CO is being produced at the Cathode. because for the CO to replace H2 is a 1:1 ratio. Hydrogen is VERY close if not a ideal gas. CO I'd assume would not be near as Ideal. So it would make sense that CO would take up a LITTLE less room for same number of moles. And at only 14.8ma I don't know if you could even seen the bubbles or not. I'd suggest checking the purity of the "H2" after a "fuel cell" run.

 

again, I don't know; just because I'm in Chem 2 now in High school. We haven't gone over electrolysis or electrochemistry just yet.

 

-Randy

[Rocket Man]

could carbonic acid to hydrogen carbonate play a role? i can imagine hydrogen carbonate would draw hydrogen gas into solution via the cathode but i'm drawing a blank as to where the other hydrogen ions go. (residual oxygen with CO2 catalyst?)

[YT2095]

well the H2 hasn`t moved at all over the last 18 hours, but over 6ml of CO2 has been absorbed and the charge is right back up again. I totally discharged it yesterday.

 

6ml later and it`s good to go again???

 

I think I`ll leave it and see what the absorbtion rate is without a load, and then compare it again with a fresh batch of gas and test the absorbtion rate With a load.

 

just to see it that makes any difference.

[insane_alien]

hydrogen ions can be absorbed at the anode with carbon dioxide(carbon dioxide has an electrode potential, wrt hydrogen which is the standard. so does carbon).

 

maybe you've made a carbon-carbondioxide electrochemical cell? how did that testing for oxalic acid go?