mewrox99
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Cheap HClO4 should I get
HMS-Beagle.com are shipping internationally 25mL of reagent grade Perchloric Acid at 70% concentration for $3.50
http://www.hms-beagle.com/xampp/htdocs/shop/index.php?main_p...
For less than a combo at McDonalds I can have one of the most interesting strong acids.
But I know that it is considered extremely hazardous. Does it fume? I use a wood workbench I assume wood + HClO4 = Trouble
What about dilution, how exothermic is it and will 10-15% still attack copper (it's an experiment i want to do)
However my main reason for buying is the preparation of perchlorates.
Is this chemical to much for a 14 year old?
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Chainhit222
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It seems reasonable to buy so long they do not fuck you with hazmat shipping charges. Perhaps prepare your own perchloric acid instead? IIRC it was a
relatively simple procedure.
It might be a good idea to pick up a few bottles of this certified perchloric acid though if you plan on using it in organic synthesis, but for
messing around you should probably just make it.
However, now that I looked into making it, maybe buying it is a better idea :-/
[Edited on 1-9-2010 by Chainhit222]
The practice of storing bottles of milk or beer in laboratory refrigerators is to be strongly condemned encouraged
-Vogels Textbook of Practical Organic Chemistry
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DDTea
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I work with HClO4 almost every day, so here's my opinion on: it's really not something you want to have in a domestic environment.
It does fume, and that can be a big problem if you have organics in the area (not just chemicals, but building materials for your work area).
Volatile organic chemicals will lead to even more trouble.
Diluting it is not bad . It gives off a lot of heat, like diluting any concentrated acid would, but it doesn't sputter too badly--even when adding
water to it (yes, I do this, even if it's bad form or whatever).
If you want to prepare perchlorate salts, my guess is that you plan to order more than 25 mL's of HClO4. If you just planned on using 25 mL's for
say, organic synthesis, that's pretty reasonable. In larger quantities, though, I'd really discourage you from keeping that around.
There are plenty of exciting things to do that won't set you on fire.
"In the end the proud scientist or philosopher who cannot be bothered to make his thought accessible has no choice but to retire to the heights in
which dwell the Great Misunderstood and the Great Ignored, there to rail in Olympic superiority at the folly of mankind." - Reginald Kapp.
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psychokinetic
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Depends on the 14yr old.
I'm 23 and you've got more chemistry under your belt than I do.
“If Edison had a needle to find in a haystack, he would proceed at once with the diligence of the bee to examine straw after straw until he found
the object of his search.
I was a sorry witness of such doings, knowing that a little theory and calculation would have saved him ninety per cent of his labor.”
-Tesla
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Fleaker
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If you need perchloric acid, it's way better to buy it than distill it--insofar as your sanity is concerned. Distilling anhydrous perchloric acid is
an experience.
As far as the 70% HClO4 goes, I would say it's fairly tame and only slightly worse than 70% nitric acid. It doesn't have a huge exotherm upon dilution
nor is it terrible reactive. The key is to keep the spatter of it away from wood benches and anything organic, and to make only stable perchlorate
salts. At 14 years old, I'd keep well away from more concentrated perchloric acid--it is a whole different animal. I compare anhydrous perchloric acid
to anhydrous nitric acid, both hurt like hell to get on you, and both will explode with anything organic.
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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mewrox99
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I might get the 25mL of 70% and very slowly dilute it to 250mL of 7%
I will do this with an ice bath, and have NaHCO3 on hand. What sort of gloves should I wear, and do I need a face shield or respirator
The 7% isn't worse than any other strong acid?
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ScienceSquirrel
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7% perchloric acid will be about as interesting as vinegar.
It will be a strongly acid solution so it will readily dissolve reactive metals like magnesium but it wil not have any oxidising properties at all.
The perchlorate anion is very stable in aqueous solution. It is thermodynamically unstable but kinetically stable eg there is a large 'hump' of
activation energy to get over before it can go downhill liberating its energy and acting as an oxidising agent.
Given the choice between 70% perchloric acid and 70% hydrogen peroxide I would go for the perchloric acid everytime 
Potassium perchlorate is very stable and dozens of other perchlorate salts of metal complexes have been prepared for crystallographic purposes.
They are used because the perchlorate anion is highly symmetric, does not act as a ligand and they generally form good crystals.
Perchloric acid does not fume as much as hydrochloric acid and I have handled it on the open bench.
As long as you are sensible eg do not add it to organic materials or heat the concentrated acid you should be fine. Drench any spills with a lot of
water, mop up and flush the wash down a drain.
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mewrox99
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At what concentration does it stop being an oxidizing hazard. I have a wooden workbench so don't want to risk a spill of the 70% stuff.
My use is to make transition metal perchlorates from their carbonates
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ScienceSquirrel
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The cold acid is not going to attack a wooden workbench as long as you dilute it quickly.
There are very few chemicals that will cause large lumps of wood to catch fire spontaneously.
Fine sawdust is a different matter and it will inflame on adding a few drops of 100% nitric acid.
Think like a chemist!
6% hydrogen peroxide, common safe disinfectant
35% hydrogen peroxide, strong oxidising agent, causes burns
80% peroxide, decomposes to steam and oxygen
100% hydrogen peroxide, will catch fire or explode with common organic materials, decomposes explosively in contact with finely divided metals.
If you are really worried, buy a high density polythene tray and do your experiments on that, give the tray a rinse when you are finished and you can
sleep easy. It is only truely mad chemicals like chlorine trifluoride that will attack HDPE at room temperature.
It is an oxidisng agent but it needs provoking, unlike liquid ozone, for instance, that will happily explode with the little bit of silicon grease
left in the bottom of your cold trap 
[Edited on 2-9-2010 by ScienceSquirrel]
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woelen
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Buying that acid for $3.50 per 25 ml is a good chance of getting some of this acid for an acceptable price.
I have quite a lot of experience with perchloric acid of this concentration, and I can tell you that it is much more benign to the skin than 65% HNO3
and 96% H2SO4. It does not attack skin like HNO3 or H2SO4, it does not inflame in contact with paper, wood, etc and it also does not react explosively
with common reductors like sodium sulfide, potassium iodide, etc.
This acid does not fume in air, not at all (its boiling point is around 200 C). If it comes in contact with skin (I have had that a few times), just
stay calm and quickly rinse with a lot of water, just like you should do with e.g. hydrochloric acid on your skin. It does hurt when allowed to remain
in contact with skin for many minutes, but it definitely is not the instant burn and destroy as told in many strong stories.
I can tell that max. 70% HClO4 is remarkably inert and it hardly is more reactive than e.g. 35% HCl. The latter is worse to handle and store, due to
the corrosive fumes. I even boiled the acid with stuff like Na2SO3 and KI. With Na2SO3 you just boil off SO2, the acid is not capable of oxidizing the
SO2. With KI the boiling hot liquid only becomes very weakly yellow, but this weak yellow color also may be due to the oxidation of iodide by oxygen
from air.
Only if you allow the acid to soak wood for a prolonged time, or if you make it more concentrated than 70% it becomes dangerous. There is a VERY sharp
contrast between anhydrous acid and the 70% acid. Anhydrous acid explodes in contact with most organics (including paper, wood, skin and solvents like
toluene, ethanol and acetone) while the 70% acid does not react or only slowly reacts. Mixing of perchloric acid with concentrated sulphuric acid is a
risky thing, because the sulphuric acid may dehydrate the acid and the resulting mix becomes very reactive. Mixing of 70% acid with water can be done
safely. Hardly any heat is produced.
So, try to order a few of these bottles. No need to dilute, that would be a waste of such a reagent. Keep in mind though that perchloric acid is not
that kewl-acid going BOOM easily as many people think it is. At 70% or lower concentration it just is a strong acid without pronounced oxidizing
properties.
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DDTea
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I should clarify what I do with HClO4 to give perspective: we use it for sample digestions (along with a few other acids--Sulfuric, Hydrofluoric,
Nitric, Hydrochloric as appropriate). The whole mess is then boiled down in a dedicated perchloric acid hood.
The fumes are really what's most dangerous, but if you're not intending to boil it, it's reasonable to work with. At room temperature though, the
fumes are non-existent. If you let it get in contact with paper or wood and then allow the paper/wood to dry, it will form heat and shock sensitive
compounds (this is how we screw around: put a small amount of HClO4 onto a piece of a paper towel, then throw it on the hot plate and watch it
explode). It's not bad when it's wet though.
In any case, I wouldn't worry about acid burns much. Good chemical handling and chemical hygiene can almost eliminate the risk. Any concentrated
acid on your skin is bad, but usually it's more of a nuisance than an emergency.
"In the end the proud scientist or philosopher who cannot be bothered to make his thought accessible has no choice but to retire to the heights in
which dwell the Great Misunderstood and the Great Ignored, there to rail in Olympic superiority at the folly of mankind." - Reginald Kapp.
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Jor
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I would really not want to ship this stuff overseas, even though they state they do so. And imagine what customs must think if perchloric acid is
detected in a package (from wich perchlorates can be made). I also wanted to order some elemental arsenic at this source but I did not, because of the
possible risk when the package is opened. Even though I want the arsenic as an element sample, I would expect customs to think that the arsenic is
most likely ordered for use as a poison.
And The Netherlands are a country where you can relatively order different exotic dangerous reagents. I have heard AUS and NZ have a lot more strict
policy, so I would not buy this stuff if I were you, because you might risk a visit by the police.
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ScienceSquirrel
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Concentrated sulphuric acid rapidly attacks skin because it is a strong dehydrating and oxidising agent as well as an acid. It quite literally rips
the molecules apart by protonation and elimination of water to leave a condensed carbon skeleton that can then be oxidised.
Nitric acid is quite a strong oxidising agent and it will nitrate as well. I believe the almost instant yellow colour of exposed skin is due to the
nitration of phenylalanine. The nitrogen dioxide is I think the corrosive agent that kills and causes exposed skin to peel off.
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Formatik
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My two cents about it below.
Note if you are going to dilute it and reconcentrate: conc. HClO4 does fume when its hot, these fumes are very, very thick and it keeps fuming until
it gets cool. These are choking fumes! The fumes are thick than H2SO4 fumes (which are carcinogenic, maybe also HClO4 fumes). These fumes can be
mistaken for a fire, because they do not disperse readily, even in a very windy area (speaking out of experience here). Keep that in mind if you are
ever concentrating the dilute acid.
I was heating perchloric acid alone in a beaker on a hotplate, and once I got a very violent ejection (spitting). I have noticed this violent spitting
in small amounts, but not larger amounts of the acid. The surrounding material was mainly stone, so I didn't have to worry about a fire.
My biggest concern is making sure it isn't stored near wood, cardboard and cellulose. Then oxidizables and all the other stuff. If I ever store
perchloric acid it is only temporarily and then it is used right away. In that case, the acid is in cement barricades (large cement blocks with
openings obtained from the hardware store) on only all concrete floors. I try to think what would happen if an earthquake hit, what it would mix with.
If you are afraid to store it, then just convert it into a salt.
Perchloric acid is a strong dehydrating agent, similar to but weaker than H2SO4 (it will turn KMnO4 into Mn2O7 though not immediately as noted by me
in the permanganates thread). I think I read somewhere magnesium perchlorate is the most effective dehydrating agent there is (depending on what you
are drying, you don't want it to go boom).
Perchloric acid is worse than nitric acid in some aspects, since pretty much anything you mix with it can turn into an explosive, probably even less
stable than nitric acid. In fact, the aqueous concentrated acid is said to go off with a booster charge alone! So avoid undue heating of the acid like
with a propane torch.
Perchloric acid can probably burn the skin, though I put a drop onto my skin of conc. HClO4 and let it evaporate, it didn't do anything. Even the
smallest amounts of conc. H2SO4 burn me almost right away. A different story for the anhydrous acid, the literature (Roscoe, Lieb. Ann. 121 [1862]
353) describes anhydrous HClO4 as an extremely corrosive acid, which leaves painful wounds on the skin that heal only after several months.
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