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galveston · Nov 25, 2009, 11:10 AM

Will hard anodize on aluminum react with:

Sulphuric acid

Hydrochloric acid

KOH

Thanks.

Unknown008 · Nov 25, 2009, 11:56 AM

Hard anodize aluminium?

You mean aluminium that has been anodized with a thick layer of oxide?

If so, I would have replied yes. Aluminium oxide is an amphoteric oxide, and will hence react with both acid and base.

Perito · Nov 25, 2009, 01:59 PM

Originally Posted by Unknown008

Hard anodize aluminium?

You mean aluminum that has been anodized with a thick layer of oxide?

If so, I would have replied yes. Aluminum oxide is an amphoteric oxide, and will hence react with both acid and base.

Correct... but it reacts fastest with strong bases (KOH in your question). It will take a while for the acids to break through the hard oxide layer.

galveston · Nov 25, 2009, 04:46 PM

Thanks.

The answer is not what I hoped for. I am looking for a material to build a reaction tank, and don't want to use stainless steel because of the expense.

Maybe there is some product that will produce a glass lining.

Unknown008 · Nov 26, 2009, 07:34 AM

That's not really my field of knowledge about the practicability (sp?) and cost. Maybe you can try some alloys that are corrosion resistant.

We use brass for taps and some pipe joints.
You can try PVC.

I don't the price at all, OK.

I would like to know however what type of reactions you'll be performing in there? Neutralisation?

Perito · Nov 26, 2009, 08:53 AM

Glass linings are usually "porcelain".

Porcelain - Wikipedia, the free encyclopedia

I've never made porcelain, so I can't tell how hard it is to use.

There are a lot of other materials of construction that are corrosion resistant. These include various versions of Hastelloy (Hastelloy B, C, etc), titanium, and many types of stainless steel. Of course, they're all expensive.

galveston · Nov 26, 2009, 09:00 AM

Originally Posted by Unknown008

That's not really my field of knowledge about the practicability (sp?) and cost. Maybe you can try some alloys that are corrosion resistant.

We use brass for taps and some pipe joints.
You can try PVC.

I don't the the price at all, ok.

I would like to know however what type of reactions you'll be performing in there? Neutralisation?

At home, do it yourself, hydrogen production.

I can get plenty of scrap aluminum free and lye shouldn't be very expensive. I have read that this kind of reaction can produce pressures nearing 1,000 psi. Use the pressure to fill tanks with hydrogen and then run a genset.

Not sure about hydrogen pressure required, but an ice engine will run on natural gas at a pressure of 4 ounces psi, so if you had a container containing 800 psi of hydrogen, you could run a 20 hp engine for nearly 24 hours.

If I don't do something, I may be looking at utility bills that I can not pay in the not too distant future.

Perito · Nov 26, 2009, 09:13 AM

Sounds too dangerous. I suggest you rethink that idea.

galveston · Nov 27, 2009, 04:57 PM

Originally Posted by Perito

Sounds too dangerous. I suggest you rethink that idea.

I can't see why hydrogen gas would be any more dangerous than propane or gasoline vapor, and we use those extensively.

Another question:

What gas is produced by mixing a base and an acid? Say, KOH and H2SO4?

Perito · Nov 27, 2009, 09:12 PM

Actually, you don't produce a gas at all

$2KOH + H_2SO_4 \rightarrow 2H_2O + K_2SO_4$

You get a lot of heat and a lot of steam. You form a potassium sulfate salt. You also form water (H+ + OH- = H2O).

Hydrogen gas is more dangerous than propane or gasoline. It's much more explosive.

http://auto.howstuffworks.com/fuel-e...le-danger1.htm

galveston · Nov 28, 2009, 02:52 PM

Originally Posted by Perito

Hydrogen gas is more dangerous than propane or gasoline. It's much more explosive.

HowStuffWorks "Dangers of Hydrogen"

Thanks for the info.

You need to explain your above comment, though. I realize that hydrogen + oygen is highly explosive, but then so is every other fuel.

When the Hindenburg was destroyed, it didn't explode, it took a fair amount of time to burn.

Unknown008 · Dec 1, 2009, 04:16 AM

Ok galveston, I have a table here:

Heat of combustion - Wikipedia, the free encyclopedia

You'll see that hydrogen, though giving off less heat than other fuels per mole of reactant (kJ/mol column), if produces much more heat than the others concerning it's weight (MJ/kg column). So, if you have the same mass of fuel, hydrogen would release more heat, hence more dangerous than any other fuel, excluding the other risks that were included in Perito's link.