Highest feasable concentration of acid?

[RyanJ]

Whats the highest (feasable) concentrations of Hydrochloric, Nitric and Sulphuric Acids?

 

I have Nitric Acid at 70% conc.

I have heard you can make Sulphuric Acid 97% conc. by boiling the sulution untill you stop seeing a white smoke.

No idea abut Hydrochloric Acid at all...

 

Anyone have any ideas?

 

Cheers,

 

Ryan Jones

[Primarygun]

Nitric acid: 70% 16M

Hydrochloric acid: 35% 11M

H2SO4 can have 98% 18M, we usually use the acid of this con. to absorb sulphur trioxide to form oleum.

The percentage shows the mass by the acid molecule, so the later measure( molarity)can show the acidic power more accurately I think.

[RyanJ]

Nitric acid: 70% 16M

Hydrochloric acid: 35% 11M

H2SO4 can have 98% 18M' date=' we usually use the acid of this con. to absorb sulphur trioxide to form oleum.

The percentage shows the mass by the acid molecule, so the later measure( molarity)can show the acidic power more accurately I think.[/quote']

 

Thanks for the information Primarygun - how is it that HCl is so much lower than the others?

 

Cheers,

 

Ryan Jones

[Primarygun]

Thanks for the information Primarygun - how is it that HCl is so much lower than the others?

You're welcome.

By the way, I heard that HF can have 35M, but it is a weak acid.

HCl is quite "thin".

[RyanJ]

You're welcome.

By the way' date=' I heard that HF can have 35M, but it is a weak acid.

HCl is quite "thin".[/quote']

 

 

Ah, right I see - thanks

 

Like was discussed in a previous theread of mine concerning the strongest acid, its not what it destroys (HF wins this one hands down) but its how well a proton donator it is

 

Cheers,

 

Ryan Jones

[woelen]

HNO3 can even be 100%. This cannot be made by distillation of dilute HNO3, due to formation of an azeotropic mix of 68% HNO3/32% water, but with other methods, 100% HNO3 can be made.

 

H2SO4 also can be 100%, but commercial H2SO4 has at most 97 .. 98% acid. This also is due to the formation of an azeotrope with water.

 

Also H3PO4, CH3COOH and HCOOH can be at concentrations of 100%, although the commercial acids usually are at 85, 80 and 85% respectively.

 

The limit of concentration of HCl is that pure HCl is a gas and the solubility of this gas is limited. Max concentration at standard air pressure is approximately 38%. It is as with carbonated softdrinks. At higher pressure more gas can be dissolved than at lower pressure. If the concentration of HCl would be higher than 38%, then the bottle would be pressurized, just as with carbonated softdrinks and as soon as such a bottle would be opened, gaseous HCl would bubble out of the solution.

I have a bottle of 37% HCl and on warm summer days, there already is quite some over-pressure in this bottle (which is a real pain, because everything near this bottle is corroded ).

 

The acid HF can be 100% and at that concentration it is a liquid, which boils at just under 20 C at standard air pressure. Pure HF indeed has a concentration over 35M, the molarity is the density of this, divided by the molecular weight of this. For water, the molarity even is 55M.

[RyanJ]

Hmm... thanks for the information woelen

 

So you are saying that the highest concentration that is possible is dependent on the compounds solubility? That makes sence and also explains how some can reach 2100% concentrated... are these liquids? As far as I cna see this is the only way to get 100% concentration

 

Cheers,

 

Ryan Jones

[RyanJ]

I also have one more question - what is supersaturation? Does it affect the concentration?

 

Cheers,

 

Ryan Jones

[xeluc]

a super saturated solution is a solution that has more solute than can normally be disolved in the solvent at a given temperature. Disolve sugar in 90 degree C water until its saturated. Since more sugar can be disolved at a higher temp. When the temp is slowly lowered to room temperature, the solution becomes supersaturated. The disolved solute in supersaturated solutions is very unstable however, and excess agitation can actually cause a precipitation of the excess sugar, making it saturated.

[akcapr]

The percent conc. of an acid is just relative to what you consider 100%. And for supersaturated solution you can make really neat crystillizations. If you supersaturate some NaAcetate and drop a seed crystal, you can watch the crystals begin to grow out fast. Really neat stuff. You can make some with vinegar and baking soda.

[xeluc]

I'm gonna go do that, Thanks AKcapr..

[RyanJ]

The percent conc. of an acid is just relative to what you consider 100%. And for supersaturated solution you can make really neat crystillizations. If you supersaturate some NaAcetate and drop a seed crystal, you can watch the crystals begin to grow out fast. Really neat stuff. You can make some with vinegar and baking soda.

 

Sounds like fun! Maybe Ill try this tomorow!

 

Cheers,

 

Ryan Jones

[sanjaygeorge]

but for H2SO4 100% conc. can't be formed due to Azeotrophysm

[sanjaygeorge]

Moreover H2so4 is a dehydrating agent!!

[xeluc]

but for H2SO4 100% conc. can't be formed due to Azeotrophysm

HNO3 can even be 100%. This cannot be made by distillation of dilute HNO3' date=' due to formation of an azeotropic mix of 68% HNO3/32% water, but with other methods, 100% HNO3 can be made.

 

H2SO4 also can be 100%, but commercial H2SO4 has at most 97 .. 98% acid. This also is due to the formation of an azeotrope with water.

[/quote']

 

Yes huh....

[woelen]

The 100% acids can be formed, but not by boiling a more dilute solution of the acid.

 

E.g. 100% H2SO4 can be made from 96% H2SO4 by adding some SO3 to it. That SO3 reacts with the water and the acid:

SO3 + H2O --> H2SO4

 

Pure HNO3 can be made by distilling 68% (azeotropic HNO3) with conc. H2SO4. 90+ % HNO3 can be made in this way, leaving the water behind in the sulphuric acid, due to its dehydrating properties.

 

Making 100% HNO3 can be done by adding N2O5 to 90% HNO3:

 

H2O + N2O5 ---> 2HNO3

 

N2O5 in turn is made by adding a large excess of P4O10 to 90% HNO3. The P4O10 takes up all water and also dehydrates some of the HNO3 (reverse of reaction shown above).

 

As you can see, making the 100% acids is not easy at all, but technically speaking, it is possible. In fact, they are available as lab reagents, although at a very high price.

 

You could even speak of over 100% acids, e.g. sulphuric acid, with excess SO3 dissolved in it, or HNO3, with excess N2O5 dissolved in it. The first one is available commercially as oleum with up to 65% of SO3 by weight, but not for the general public.

[RyanJ]

The first one is available commercially as oleum with up to 65% of SO3 by weight, but not for the general public.

 

I wonder why? I suppose its because you don't really need something that concentrated for normal applications?

 

I bet you could make your own in the way you described though it would be quite exothermic and very dangerous! I think I'll stay with my 97% conc. Sulphuric Acid

 

Cheers,

 

Ryan Jones

[The Thing]

I believe hydrochloric acid can be concentrated to JUST ABOUT 40%, but then it would be fuming profusely.

[akcapr]

How is H2so4 a dehydrator, is it just the molecules of water that grab it after it ionizes or what?

[RyanJ]

How is H2so4 a dehydrator, is it just the molecules of water that grab it after it ionizes or what?

 

 

I'm not shure how but thatd what its used for

 

Have you ever added sulphuric acid to sugar? You get a big black mass, the sulphuric acid has actually pulled the water out of the compound!

 

And again in another expermients where a gas needs to be dried, its bubbles through sulphuric acid...

 

Like I said I have no idea why it does this (Maybe one of the mods can help you out on that) but I know it is a very useful property

 

Cheers,

 

Ryan Jones

[woelen]

I wonder why? I suppose its because you don't really need something that concentrated for normal applications?

 

When you add some oleum 65% to water, then it explodes, spraying around concentrated sulphuric acid and boiling water.

 

If you get a drop of this on your skin, then instantly, you have a deep black charred wound.

 

If you open up a bottle of 65% oleum, then you'll see an incredibly thick white plume of smoke. Open such a bottle in a normal living room. Within two or three minutes, you'll not be able to see the wall at the opposite side of the room. Besides that, the fumes are extremely corrosive and eat away your wall-paper, metal objects, your lungs, etc.

 

You understand, why this stuff has no domestic applications?

It only can be used in carefully designed reaction chambers (such as in industry) or in well-designed and very powerful fume hoods.

[sanjaygeorge]

It may be due to the property of azeotropism

[RyanJ]

You understand' date=' why this stuff has no domestic applications?

It only can be used in carefully designed reaction chambers (such as in industry) or in well-designed and very powerful fume hoods.[/quote']

 

Oh yea makes perfect sence too me... what in gods name would you need something like that for? Shurly Conc. sulphuric acid should do the job just as well?

 

Cheers,

 

Ryan Jones

[woelen]

Oh yea makes perfect sence too me... what in gods name would you need something like that for? Shurly Conc. sulphuric acid should do the job just as well?

 

Cheers' date='

 

Ryan Jones[/quote']

There are applications, but those are purely industrial. In fact, SO3 and oleum are among the chemicals used most in industry and they are produced and used in megatonne quantities each year.

 

Many commercial nitrating processes require the use of nitronium salts (NO2(+)). These can be made by adding HNO3 to oleum:

 

SO3 + HNO3 ---> HSO4(-) + NO2(+)

 

Many ester-forming reactions produce water and even sulphuric acid is not sufficiently dehydrating for these. The use of oleum opens up the formation of such esters very smoothly, because the water is taken up at once by the SO3 and the equilibrium is drawn smoothly towards the ester-side of the reaction.

 

Oleum also is used for making many dyestuffs, fertilizers and explosives. In fact, there are many uses of this versatile chemical in industry.

[Primarygun]

Is oleum more dangerous than con. sulphuric acid?

Does it relate to their oxidation no. of the sulphur?