Sciencemadness Discussion Board - Testing for hydrogen.....

Testing for hydrogen.....

solo - 18-9-2007 at 09:16

I have recently had the need to use compressed Hydrogen for a hydrogenation reaction.......all the chemistry was done fresh catalyst was used but the hydrogenation uptake failed 4-5 times even though fresh catlayst used each time. Tested for making sure the compound had been chlorinated using the copper burn test and sure enough the copper soaked material did burn with a green flame.......I focused on the Hydrogen source I, hence filled a balloon, but the ballon after released found itself on the ground instead of the ceiling as all light gases should rise.

I tried the filled balloon test then at a safe distance ignited it with a candle and it did pop but not sure if it was the pop of the balloon or the gas igniting pop.

So I'm looking for an alternate method of testing this gas.....I feel the dealer was less than honest with the claims of the contents........solo

P.S.I just did the test tube amber test and no pop......

[Edited on 18-9-2007 by solo]

stoichiometric_steve - 18-9-2007 at 09:40

seems like you've been bullshitted. get a gun and take the fucker down!

garage chemist - 18-9-2007 at 10:15

Lighting a hydrogen baloon with a candle makes a big impressive fireball. You will absolutely know if the baloon contained hydrogen.
COmpare with a hydrogen baloon filled with hydrogen from e.g. NaOH/Al reaction.
So its probably the gas that is the problem.
Where did you get that cylinder? It would be really strange to get a gas cylinder that contains something else than what it lists on it!

solo - 18-9-2007 at 11:16

No fireball.....however what impressed or didn't impress me is the inability of the purported hydrogen filled baloon to rise once release after securing, as light gas hydrogen gave rise to the blimps back then prior to changing the gas to a non flamable helium.........solo

chemkid - 18-9-2007 at 14:15

what kind of baloons are you using? How big are they? Your ballon just might be too heavy. Burning well, who knows why the hydrogen won't burn.

I agree with stoichiometric_steve, you were probably bs.

Chemkid

solo - 18-9-2007 at 14:18

I tend to agree with stoichiometric_steve......and the balloon is the regular size balloon thanks for helping me confirm that i got taken for a ride into the wasteland........................solo

not_important - 18-9-2007 at 17:26

The simple tests are -

bubble some through soapy water, see if the bubbles float. The stream of gas must be adjusted to generate free bubbles. This removes the question of the type of balloon.

try igniting some of the bubbles with a long match.

Try igniting a stream of the gas from a narrow jet, probably should have some anti-flashback arrangement. Hydrogen will burn with a pale blue nearly invisible flame, organics give flames with strong blue, yellow, or white regions.

Measure out a few cc of the gas at STP, using an inverted container in a gas trough or whatever. Once the volume is noted let it bubble into a container with a measured severalfold excess of air, and spark it several times to get all the hydrogen to combine. Let it cool back to the original temperature and measure the new volume, that will let you calculate the amount (if any) of hydrogen in the gas.

I've seen gas cylinders referred to as "hydrogen" by workers using them, that are actually filled with thermally cracked ammonia - 3 H2 to each N2.

chemrox - 18-9-2007 at 22:36

thermally cracked ammonia? no shit?

It's clear Solo got burned. I'm amazed but there is no other conclusion. Hydrogen lifted the Hindenburg and all the other Zeppleins. The Hindenburg became a fireball and it was no "light baloon."

solo - 3-10-2007 at 15:14

Took the tank back to the merchant and tested other tanks with a 6"balloon filled and the balloon dropped to the ground it never rised .....now am I mistaken that hydrogen gas is not light enough to lift the weight of a 6" balloon filled with hydrogen?........solo

Axt - 3-10-2007 at 17:04

Quote:

Originally posted by solo
Tested for making sure the compound had been chlorinated using the copper burn test and sure enough the copper soaked material did burn with a green flame

Thats the wrong way around, it should be <a href="http://www.sciencemadness.org/talk/viewthread.php?tid=4282&page=1#pid53572">blue if chlorine is present</a>, green without.

Quote:

Originally posted by solo
am I mistaken that hydrogen gas is not light enough to lift the weight of a 6" balloon filled with hydrogen?

6" doesnt seem very big, but I would still think yes. A common "party" balloon of hydrogen lifts rapidly. As Garage Chemist suggested why not produce it yourself via NaOH/Al and compare the two?

[Edited on 4-10-2007 by Axt]

solo - 3-10-2007 at 19:08

Quote:

[Quote]

Thats the wrong way around, it should be blue if chlorine is present, green without.

.............review the Beilstein Test,

http://www.hc-sc.gc.ca/cps-spc/prod-test-essai/method/chem-c...

[Edited on 3-10-2007 by solo]

stoichiometric_steve - 3-10-2007 at 22:05

Quote:

Originally posted by solo
Took the tank back to the merchant and tested other tanks with a 6"balloon filled and the balloon dropped to the ground it never rised .....now am I mistaken that hydrogen gas is not light enough to lift the weight of a 6" balloon filled with hydrogen?........solo

you really should make some H2 with acid and metal, hydrogen sure lifts up a balloon of that size. 6" is not that big.

chromium - 4-10-2007 at 04:23

Quote:

This is very strange. Party ballons fly without any problem if they are filled with pure hydrogen. I have done this with half-filled ballons that were even smaller than yours. Maybe your hydrogen is actually mix with something like nitrogen or argon? Or maybe your ballon is exceptionally heavy?

Other properties that might help to identifiy hydrogen: It burns with very pale flame, room must be dark for flame to be visible, if you deliver hydrogen gas into soap water then you get bubbles that will go airborne if they are big enough, if you touch small bubles with burning match, you will hear loud pops. Its also characteristic to hydrogrn that it slowly goes through many substances. Party ballon will lose part of its contents with some hours an PET bottle will do the same with some days.

Edit: Maybe you should ask merchant what is common use of his hydrogen. If its for some technical uses it may be just called "hydrogen" although actually is some mixture. For example where i live gas for small torches is usually called "propane" although it never is pure propane - usually mix of propane and butane but in some cases propylene (!) and may even contain 20% of acetone.

[Edited on 4-10-2007 by chromium]

[Edited on 4-10-2007 by chromium]

leu - 4-10-2007 at 16:55

It's better to do thorough library research and be able to give definitive and exact answers than waste bandwidth speculating

A liter of hydrogen weighs .09 grams

A search through the appropriate literature published before the Hindenburg disaster shows an equivalent weight of hydrogen will lift 13.4 equivalent weights of balloon equipment

The gas that's in that tank can't be hydrogen and therefore the merchant owes the customer a refund