Sciencemadness Discussion Board - Never knew you can get H2 so easily

Never knew you can get H2 so easily

KonkreteRocketry - 20-2-2013 at 06:23

This video seems legit

I never knew making H2 could be as simple as this, from hot Sodium carbonate water solution and aluminum foil, the sodium carbonate could be replaced by ethanol for this reaction, im not sure but i guess sodium bicarbonate could also do this..

I think its cus the solution dissolve Al2O3 away and aluminum react with water.

http://www.youtube.com/watch?v=ggPWdwcsyqM

Adas - 20-2-2013 at 08:27

I use NaOH when I perform this reaction. It should be faster.

Morgan - 20-2-2013 at 08:47

I bought some sodium carbonate once from the pool supply section of a hardware store. Maybe the fumes wouldn't be as noxious as NaOH or less likely to eat your hand if you're careless or not wanting to make an "elaborate" hydrogen collection device. This was in the comments.

NurdRage 3 years ago
"Aluminum is "amphoteric", it dissolves in both acids and bases and is a powerful reducing agent, strong enough to generate hydrogen from water. It is for this reason it is used for for cleaning silver, as it can reduce silver sulfides to silver metal.
You're getting hydrogen and i'm not getting it (in my video) because you're using sodium carbonate while i used sodium bicarbonate."
"Sodium carbonate is more basic than sodium bicarbonate and is strong enough to activate the amphoterism of aluminum."

[Edited on 20-2-2013 by Morgan]

DraconicAcid - 20-2-2013 at 09:01

Quote: Originally posted by KonkreteRocketry

I never knew making H2 could be as simple as this, from hot Sodium carbonate water solution and aluminum foil, the sodium carbonate could be replaced by ethanol for this reaction, im not sure but i guess sodium bicarbonate could also do this..

Why do you think ethanol would do this? Ethanol isn't a base (at least, it's not a base in aqueous solution).

blogfast25 - 20-2-2013 at 09:09

DA:

He sees ethanol as a weak acid, which it is (it's also a weak base: like water it can deprotonate but also accept a proton). It forms ethoxides with strong alkali like NaOH, KOH etc: e.g. KOC2H5 (KOEt). But it's far too weak an acid to attack aluminium in any meaningful sense of the word. But the alkali metals are readily attacked by most small primary alcohols, with evolution of hydrogen, a laboratory technique to safely get rid of left-over alkali metals.

[Edited on 20-2-2013 by blogfast25]

KonkreteRocketry - 20-2-2013 at 09:16

Quote: Originally posted by DraconicAcid

Quote: Originally posted by KonkreteRocketry

Why do you think ethanol would do this? Ethanol isn't a base (at least, it's not a base in aqueous solution).

Umm seems ethanol probably could not, but it might speed up if added, cus it dissolves the Al2O3 for the aluminum to be exposed.

DraconicAcid - 20-2-2013 at 09:24

Quote: Originally posted by KonkreteRocketry

Quote: Originally posted by DraconicAcid

Quote: Originally posted by KonkreteRocketry

Why do you think ethanol would do this? Ethanol isn't a base (at least, it's not a base in aqueous solution).

Umm seems ethanol probably could not, but it might speed up if added, cus it dissolves the Al2O3 for the aluminum to be exposed.

And you expect Al2O3 to be more soluble in ethanol than water because...?

Ethanol is an organic solvent- it is much better at water at dissolving organic molecules and nonpolar molecules. But Al2O3 isn't a nonpolar molecule, it's a network covalent solid ( http://en.wikipedia.org/wiki/Network_solid ), which means that it will basically not dissolve in any solvent that doesn't react with it. It will dissolve in strongly basic aqueous solutions due to the formation of aluminate ions; it will dissolve in acidic solutions by forming water and aluminum ions. Ethanol is barely acidic and barely basic (it can react with very strong acids and bases, but not in aqueous solution), so it will do neither.

AJKOER - 20-2-2013 at 19:52

OK, CH3OH dissolves Al, but only if there is no (or very little) water present (dry CH3OH). Again, to a lesser extent with Ethanol, but a complete waste of 200 proof alcohol!

vmelkon - 22-2-2013 at 07:58

Quote: Originally posted by KonkreteRocketry

I think its cus the solution dissolve Al2O3 away and aluminum react with water.

From my chemistry textbook, , CO3(2-) ion acts as a base to a certain extent.

CO3(2-) + H2O <=> HCO3(-) + OH-

so the reaction generates hydroxide ions, therefore, carbonate solutions are expected to be a little basic.

From there, hydroxide reacts with Al2O3 to make aluminate ion and I guess Al reacts with water.

ScienceSquirrel - 22-2-2013 at 15:19

I suspect that the reaction of sodium carbonate in aqueous solution and aluminium metal will produce a mixture of hydrogen and carbon dioxide as gases and an aqueous solution of sodium aluminate.

AJKOER - 22-2-2013 at 18:21

Performed the reaction of dissoving Al in a dilute solution of NaHCO3. A white flake precipitate form of Al(OH)3 is slowly formed over days. The Al2O3 is permeated by drop in pH permitting the following reaction:

2 Al + 6 H2O --> 2 Al(OH)3 (s) + 3 H2 (g)

Now, Na2CO3 is more basic than NaHCO3, so it is still possible that an aluminate could form, but not apparent by the NaHCO3 reaction.

AndersHoveland - 23-2-2013 at 03:03

I tried to dissolve aluminum with sodium carbonate, the reaction is very slow. I could not make enough hydrogen to collect any of it.
Sodium hydroxide reacts much faster, and the reaction can be very vigorous.

Morgan - 23-2-2013 at 17:34

Out of frustration I just now went out into my shed and got a bottle of sodium carbonate/pH adjuster. I then used a small beaker and filled it with 150 ml of water and heated it in the microwave. Two tablespoons of sodium carbonate was added and stirred. It completely dissolved. Some crumpled up Al foil was placed inside the beaker and instantly the reaction took off. I then tried to light the bubbles and also collected the gas in an inverted cup. It was very hard to get any hydrogen to light, much like in the video, but you could tell it was there, an occasional weak pop could be heard or the flame from the lighter was briefly excited by the gas.
I also noticed a slight noxiousness to the air, not like CO2 however. Perhaps the steamy mist was carrying some of the sodium carbonate into the air, akin to how NaOH in hot water becomes annoying. I wonder if magnesium would be any better? Powdered Al or Mg might be more dramatic.
Using hot water and a strong solution really eats up the aluminum. Kind of impressive.

So I went back and tried the experiment again this time using a canning jar lid almost occluding the top of the 200 ml beaker except for the lip whereupon I was able to get a weak woof sound as the gas was lit with a lighter and the flame front traveled inside the jar.
I happened to see a half gallon milk carton of Tri-Sodium Phosphate all purpose cleaner/powder in my laundry room so I tried that too. It seemed to work just as well as the sodium carbonate in attacking the aluminum. I only immersed the aluminum for a very short time, not knowing what the reaction might be. I wonder if TSP contains any traces of fluoride?
http://creationwiki.org/Sodium_phosphate
http://www.freepatentsonline.com/2220818.html

[Edited on 24-2-2013 by Morgan]

vmelkon - 24-2-2013 at 15:27

Quote: Originally posted by Morgan

I wonder if TSP contains any traces of fluoride?

What does fluoride do to aluminum?
If it contains OH-, yes, it will attack the oxide layer on Al.

SM2 - 24-2-2013 at 16:18

The most economical way of making H2 is to activate your Al surface with an Hg salt (chloride, sulphate), and place into water. No need for Lye, no need for washing soda. Aluminum, when properly exposed, will react with water with the vigorous evolution of H2. The white-ish powder which forms as a scum on the bottom, is mostly Aluminum OXide. Oh with traces of HG, etc.

Morgan - 24-2-2013 at 17:10

What would you get if you mixed sodium carbonate with tri-sodium phosphate?

vmelkon - 24-2-2013 at 18:28

You still get sodium carbonate and trisodium phosphate.

[Edited on 25-2-2013 by vmelkon]

Morgan - 24-2-2013 at 18:51

So since both alkalis vigorously dissolve aluminum in hot water, would you think both alkalis mixed would dissolve aluminum?

Lambda-Eyde - 24-2-2013 at 19:14

Quote: Originally posted by SM2

The most economical way of making H2 is to activate your Al surface with an Hg salt (chloride, sulphate), and place into water. No need for Lye, no need for washing soda. Aluminum, when properly exposed, will react with water with the vigorous evolution of H2. The white-ish powder which forms as a scum on the bottom, is mostly Aluminum OXide. Oh with traces of HG, etc.

Considering how piss cheap lye is, you'd have to be a really cheap bastard to use Hg salts instead. Solutions containing mercury are a nightmare to have around and dispose of. I would (and you should) much rather use a few bucks on lye instead of having to deal with a solution of one of the most horrifying heavy metals that you can get your hands on...

[Edited on 25-2-2013 by Lambda-Eyde]

Morgan - 25-2-2013 at 07:51

I was reading about some TSP products on the market. You can still buy pure TSP of course but it's less common I gather. Ebay has some for cheap. This first product contains 75-80% TSP and 20-25% Sodium sesquicarbonate according to the msds.
http://www.hardwareandtools.com/Savogran-10621-TSP-Lb-Heavy-...
http://en.wikipedia.org/wiki/Sodium_sesquicarbonate
http://m1.cdn.hardwareandtools.net/04/049542106214.pdf?Expir...
This next product is a mixture of TSP and sodium carbonate of unknown proportion.
http://www.dap.com/product_details.aspx?product_id=320

"Even cleaning products labeled as TSP may contain other ingredients as well, and may, in fact, be less than half trisodium phosphate.[9]"
http://en.wikipedia.org/wiki/Trisodium_phosphate

In conclusion, my box of TSP, although very old, may have contained sodium carbonate as well. I couldn't find it listed. It's a Bondex brand "The First Choice of Professionals" "all purpose" in a half gallon carton.