Jump to content
Acidoz

Sulphuric acid

Recommended Posts

I don't know where, but don't get too concentrated. 18 Molar (Pure, almost) Sulphuric acid is almost completely non-corrosive (as in, you can transport it in cast iron pipes). Acidity comes from it being diluted with water (simularly, solid acids are non-corrosive in their pure form, sulphuric happens to be a liquid when pure). So get maybe 12-14 Molar.

(We have some in the garage actually. The backup battery system on our sump pump needs to be filled manually, look into that).

Share this post


Link to post
Share on other sites

Sodium bisulfate, powder, is the least expensive and safest way to make up a large batch....pool supply stores usually carry it, or masonry contractors...we also use it to clean/etch metals, like removing firescale and such....the powder is benign until mixed with water. You also have a certain amound of control over the dilution, with your mix ratio.

Kodiak-

Share this post


Link to post
Share on other sites
I don't know where, but don't get too concentrated. 18 Molar (Pure, almost) Sulphuric acid is almost completely non-corrosive (as in, you can transport it in cast iron pipes). Acidity comes from it being diluted with water (simularly, solid acids are non-corrosive in their pure form, sulphuric happens to be a liquid when pure). So get maybe 12-14 Molar.

18M sulfuric acid is highly corrosive and will blister the snot out of you if you spill it on you. It will also tear up some otherwise non reactive materials. It was one of the few things that left a mark on the materials we tested for the counter tops in our new chemistry lab. That and 12M nitric. Very nasty stuff.

Share this post


Link to post
Share on other sites

Car batteries are a pretty good source as well. Especially those do it yourself ATV battery kits. Try to keep the acid in a glass container as much as possible. Lower molarity acids can be stored in plastic but all the higher molarities should be stored in glass.

Share this post


Link to post
Share on other sites

18M H2SO4 does not corrode metal easily, but it will burn your skin because it can catalyse the splitting of peptide bonds and lipid bonds. It's also monumentally hygroscopic, so it'll dehydrate just about anything.

I'm not worried about the concentration, as long as its higher than I need. I can always dilute it. Sodium bisulfate sounds good. I'm not really into buying large numbers of lead acid kits. I get nervous when there's lead lying around nearby. I'm still going to see if I can find a supplier of pure liquid acid though. Unfortunately it's not exactly off-the-shelf material. I also need to figure out a relatively resistant plastic because a 15L glass bucket isn't just lying around in my garage.

Share this post


Link to post
Share on other sites

My geography of australia is weak, but unless you live way out in the sticks you should have some type of shops nearby that do such things.

Look up in the phone book anodizing shops. Most will be happy to just sell you a few liters, maybe even give you some pointers too. Large shops buy acid by the ton, they are usually willing to spare some to a fellow anodizer.

Share this post


Link to post
Share on other sites

acidoz: lead acumulators (car batteries, especially that charged) and school labs:D

and to dissolving metals: I think that it is similar to HNO3. when the concentration is really high, it reacts only on the surface.

and don't be worried about lead. it isn't so toxic as other poisons you eat and breathe are ;-)

and another tip: if you have some brown coal to burn, you can make it by dissolving the fumes in water;-)

Share this post


Link to post
Share on other sites

What are you talking about...high concentration HNO3 will attack most metals violently...I know it is used to passivate stainless and in fact won't touch even aluminum foil though...this is mostly because at high concentration, HNO3 is a potent oxidizer and forms a resistant oxide surface on those materials. Sulfuric acid will not attack many metals in 18M concentration because it forms a layer of sulfate salt (like ferrous sulfate formed in an iron vessel) on the surface which will not dissolve into the sulfuric acid due to the like ion effect. If you add water, the protective layer of sulfate dissolves allowing further attack.

Lead isn't really that bad if you are careful, but given the stink that people put up about zinc on this board....I'm not even going there.

You should be able to find high strength sulfuric acid as drain cleaner, but this varies widely by location. You do not want "buffered" sulfuric acid though....certain brands are better than others but all are higher than 90% concentrated.

If only making H2SO4 were as easy as brown coal fumes....likely what you are making is sulfur dioxide from sulfur contamination. You need to oxidize that further to make sulfuric acid via catalysis or via a powerful oxidant like hydrogen peroxide or ozone....a very very longstanding and so far not remotely satisfactorily finished project on my chemistry forum.

Most plastics should be more than resistant enough for you. HDPE would probably be the best though.

Share this post


Link to post
Share on other sites
18M sulfuric acid is highly corrosive and will blister the snot out of you if you spill it on you. It will also tear up some otherwise non reactive materials. It was one of the few things that left a mark on the materials we tested for the counter tops in our new chemistry lab. That and 12M nitric. Very nasty stuff.

What makes acids acidic, are the loose Hydronium (H3O+) ions in solution. If you have pure sulphuric, there is no water for the Hydrogen Ions to attach to, so it remains as H2SO4, instead of doing this.

H2SO4 + 2H20 -> SO4(2-) + 2 H3O+

However, there's water on your skin for it to form a solution with, and that doesn't mean that H2SO4 isn't unstable enough to react with reactive metals in this form. It's still highly dangerous, but it isn't anywhere as corrosive as say, 14M H2SO4. The difference between it and pure Nitric Acid (HNO3), is that Nitric acid is formed by a gas. So 14M Nitric is as high of an H3O+ concentration as you can get, making it highly corrosive in this form. That and the NO3- Ions are highly reactive by themselves. Whereas pure H2SO4 is a liquid, and doesn't have any water to form a solution with, and thus is less reactive.

(For the cool, but unbelievably dangerous factor, pure H2SO4 poured into water can sometimes make it boil).

Share this post


Link to post
Share on other sites

(For the cool, but unbelievably dangerous factor, pure H2SO4 poured into water can sometimes make it boil).

Try it the other way around. Add the water to the acid. It will be a considerably more violent boiling.

Share this post


Link to post
Share on other sites

Thanks Sleeper I'll have a look at SigmaAldrich.com.

Try it the other way around. Add the water to the acid. It will be a considerably more violent boiling.
That could be quite fun. But I think I value my eyes more than that.
H2SO4 + 2H20 -> SO4(2-) + 2 H3O+
Since we're being technical here the pKa of the first reaction is much lower, and is why sulfuric is considered a strong acid. The pKa of the second reaction is considerably higher:

H2SO4 + H20 -> HSO4- + H3O+ pKa = -2.0

HSO4- + H20 -> SO4(2-) + H3O+ pKa = 1.92

For comparison, the pKa of HNO3 = -1.64

acetic acid pKa = 4.8

Share this post


Link to post
Share on other sites

You probably can buy from Sigma Aldrich, as long as you aren't trying to buy anything too volatile, as that will win you all sorts of red flags. On that record, pure nitric acid will be a lot harder to find than pure sulfuric, as it is more corrosive, hazardous, and is essential for making explosives. One other thing, here in the states anyway, most drain cleaners are some form of sodium hydroxide (lye) not acid at all, so just be careful.

Share this post


Link to post
Share on other sites
On 1/21/2008 at 11:33 PM, Sleeper said:

You could try SigmaAldrich.com. That's where we get most of our chemicals as they are a sulfuric acid supplier  as well. I don't know if they will sell to non-academics, but it's worth a try.

1

There have been so many changes that have taken place since 2008 in SigmaAldrich. Though it has been a long time that this thread was started, the company referred in the quote has taken up so many different activities and launched new things like ChemNavigator, Cell Marque and worked with Research technology Corp, BioReliance, etc. It has also developed many subsidiaries which I think is great when the market for sulfuric acid is so huge. I would love if the guys who had previously commented here to come back and answer again. Things have changed so much in the last ten years. The demand for sulfuric acid has increased tremendously due to the growth of sulfuric acid fertilizers worldwide.

Edited by Stephbaker

Share this post


Link to post
Share on other sites
On 01/21/2008 at 9:07 AM, Hadovec said:

a

n't be worried about lead. it isn't so toxic as other poisons you eat and breathe are ;-)

a

Wot he sed.  Jeeze, guy, you're reckoning on keeping 15 liters of well concentrated H2SO4 and you're antsy about metallic lead??  Further homework is called for.  You haven't assessed your risk right.

Just don't dip the lead in your orange juice and drink it.

Also be glad you're not handling nitric acid.  The stuff *can* be handled safely, lab gloves, aprons, tight containers, but spills are savage to living flesh, and highly unrecommended.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×