Sciencemadness Discussion Board

60-100 % ???

DrNewbee - 5-8-2015 at 11:13

Hey guys.

I know it might sound like a true newbie question but i have searched the web and cant seem to find an answer... i have bought one liter sulphuric acid wich is clear and clean...on the side of the bottle it says : contains sulphuric acid 60-100%. That is a 40% difference! I assume it is a standard way for the company distributing it to protect themselves from the danger that a person using it with the assumption that it is 100% hurting themselves. ..i dont know..

Any one know?

Thx again

annaandherdad - 5-8-2015 at 11:22

I'd be more worried that it contains something besides sulfuric acid and water. Where did you get it? (A common source for cheap sulfuric acid in the US is drain cleanear. It is usually contaminated with carbon and other junk.)

[Edited on 5-8-2015 by annaandherdad]

DrNewbee - 5-8-2015 at 11:28

Yeah drain cleaner supply shop...but they acctually dont sell it anymore..they had to order it for me from a supplier and they tried to covince me that the other products they had worked just as well as the one i wanted wich should contain only water and sulphur...the labeling is very strict where i come from so i dont believe that there are any contaminants in it as that is something they would have had to inform the user about...but hey what do i know....i wonder if any of you out there have come across the 60 -100% labeling...

[Edited on 5-8-2015 by DrNewbee]

Bot0nist - 5-8-2015 at 11:36

Put a drop onto some dry paper, like toliet paper or note paper. If it is in the 90% range, some charing should be seen on the paper at roomtemp. 60% sulfuric acid will only moisten it, maybe unless th acid is very hot.

Check the reaction, on a very small scale, of your acid with NaCl (table salt.) If it fizzles and produced HCl easily, then your acid is fairly concentrated.

Or tirate it with a known solution of alkali, like NaOH or whatever is handy.

Fret not, strong boiling of the acid in an appropriate glass(boro) container will eventually drive off a good fraction of the diluting water. As the concentration of the H2SO4 increases along with the solutions boiling point, choking and dangerous white mists and fumes will be produced, for a good while, before a concentration of >= 90%. Don't expect anything much higher than around 90% using this method, any higher requires more expertise, like vacuum distillation, or generating SO3 to bubble through it.

So, if it turns out that what you have is too diluted for your uses, you can get your diluted acid from the claimed.minimum to up to around 90% with with minimal equitment and some time and effort. Easy enough, but not without some risks. Very real nhalation risks while boiling the acid of course, and the fact that boiling concentrated sulfuric acid will completely destroy human tissues right before your eyes if some accident happened, or you spill it on yourself. Just be mindful and work slow. Read on this forum, about concentrating battery acid. Hundreds of threads exist, I'm sure. Do your research and absorb. Use The Forum Search Engine. ;)

If it's clear and concentrated sulfuric acid drain opener, then I have found it works for almost all purposes, exempt maybe for analytical or very delicate reactions I assume. I've used the pink and dark brown/black ones in some cases when the purity of the acid is of no concequense.
Most likely, any use in organic chemistry would probably require distilation, or purchasing tirated reagent grade sulfuric acid solutions.



[Edited on 6-8-2015 by Bot0nist]

DrNewbee - 5-8-2015 at 11:46

Thx man!

I will try that out and then give you a feedback!

Bot0nist - 5-8-2015 at 12:02

It's labeled with the concentration range so wide, likely because the bottler and seller were unsure of the specific concentration of each batch. Considering its intended use and the source of and previous applications of the acid, they have no need to tirate each batch, or be concerned about darkening from contamination for that matter.

Sulfuric acid that is used as drain opener is often the byproduct of other processes utilizing your acid first, like metel pickling or many other industrial uses. That is why carbon, iron, and other "gunk" can darken or discolor the acid. Clear acid is a good sign though. It will likely darken considerably, if it happens to be 60% and you boil it to concentration. If it is already around 90%, clear and slightly viscous, you are probably in luck.

Rooto drain opener is a prized brand around here, being known for usually being very clean and quite concentrated right out of the bottle.

Be safe, and keep us updated on your testing. It's better to read and ask questions than to overlook or not know some little thing, that could become a real problem. Example, don't put water in your hot, concentrated sulfuric acid. Even adding some water to roomtemp or slightly chilled sulfuric acid will make splattering acid, mists, pops and splashes. Boiling concentrated sulfuric acid would, in effect, explode all over everything, as the added water flash boils on contact to the hot H2SO4.

[Edited on 5-8-2015 by Bot0nist]

Metacelsus - 5-8-2015 at 15:17

You could also check the density as another way of roughly determining the concentration.

Volanschemia - 5-8-2015 at 15:37

https://www.sciencemadness.org/whisper/viewthread.php?tid=61...

A thread on determining the concentration of Sulphuric Acid from drain cleaner and concentrating/purifying.

Bot0nist - 5-8-2015 at 16:49

^^^
There are many good threads on that or closely related threads. The one you linked is a nice exaple of a good one. So, the OP has much to read. That's why I standby my advice that the OP should start by UTFSE. ;) This site is a wonderful resource. Much more so if you have the tenacity to rummage through the many years of questions and posted experiences.


diddi - 5-8-2015 at 17:11

check the boiling point. there are graphs online which correlate BP with concentration.

[Edited on 6-8-2015 by diddi]

annaandherdad - 5-8-2015 at 19:24

Australian Scientist: Thanks for the link, I read the thread and found it very interesting. It's just what this poster needs.

But the thread rambles a lot, and doesn't get summarized. My summary would be that the best way to measure the concentration of H2SO4 would be density measurement, if you're sure that the only contaminant is H2O; otherwise titrate. And for titration, the conclusion seems to be that you must first titrate your NaOH with oxalic acid, and then use that to titrate the H2SO4. Otherwise you can't rely on your NaOH being completely dry. I suppose that's why they sell NaOH solution at guaranteed molarity, it would save a lot of trouble. Someone also mentioned using Na2CO3. I just wanted to say about that, that when I compare washing soda I buy in the hardware store with Na2CO3 I get from a chemical supply house, the former seems to me to have a small amount of soap or something in it.

BTW, I, too would have thought that NaOH did not form regular hydrates (with a definite number of water molecules per NaOH), but Bert's phase diagram seems to say that I'm wrong.

DrWhooo - 8-8-2015 at 14:32

Quote: Originally posted by Bot0nist  


Be safe, and keep us updated on your testing. It's better to read and ask questions than to overlook or not know some little thing, that could become a real problem.

[Edited on 5-8-2015 by Bot0nist]



1ml of h2so4 was weighed and it was 1.80g...
If 1ml of 99% h2so4 is 1.84 g then:

1.84/99 = 0.0185
1.80 × 0.0185 = 97.3

Does this seem right?


[Edited on 8-8-2015 by DrWhooo]

Oscilllator - 8-8-2015 at 21:40

Quote: Originally posted by DrWhooo  
[/rquote]
1ml of h2so4 was weighed and it was 1.80g...
If 1ml of 99% h2so4 is 1.84 g then:

1.84/99 = 0.0185
1.80 × 0.0185 = 97.3

Does this seem right?

I'm not sure where you got those numbers from. Using this sulfuric acid density table I get a concentration of 87% H2SO4, which sounds more plausible to me, considering its source.
What did you use to measure out 1ml of sulfuric acid? Concentrated sulfuric acid can be a little viscous, so it you used a 1ml pippette or similar, it is likely some acid remained behind. I usually use a 100ml volumetric flask for my density calculations, and that gets me 4 significant figures when I weigh it on my 1kgx0.1g scale.

DrWhooo - 9-8-2015 at 03:37

Quote: Originally posted by Oscilllator  
Quote: Originally posted by DrWhooo  
[/rquote]
1ml of h2so4 was weighed and it was 1.80g...
If 1ml of 99% h2so4 is 1.84 g then:

1.84/99 = 0.0185
1.80 × 0.0185 = 97.3

Does this seem right?

I'm not sure where you got those numbers from. Using this sulfuric acid density table I get a concentration of 87% H2SO4, which sounds more plausible to me, considering its source.
What did you use to measure out 1ml of sulfuric acid?


First off thx...

The numbers i got from h2so4 density being 1.84g/ml...
My h2so4 weighed 1.80g/ml...
I divided the weight (1.84g) with 100 to get the denisty for 1%
Then i added my h2so4 s weight (1.80g) with the 1%...

Seems right to me but given the detail you mentioned with acid staying behind i guess it must be off. I used a syringe to mesure 2ml and divided by half.

And the chart you reffered to is density in 60F , i mesured in room temperate..

Thx again

Bot0nist - 9-8-2015 at 17:42

DrWhooo, does it char paper when dripped on it, or does it react with table salt readily?These quick tests are not nearly as accurate as density readings, but they are a fast, easy, and reliable means to know if your "in the ballpark."

DrWhooo - 10-8-2015 at 05:06

Quote: Originally posted by Bot0nist  
DrWhooo, does it char paper when dripped on it, or does it react with table salt readily?These quick tests are not nearly as accurate as density readings, but they are a fast, easy, and reliable means to know if your "in the ballpark."


Sorry i havent yet got to doing that..i m waiting for my pipette from ebay first...dont want to fuck up with H2SO4...but i will post here as soo as i do...till then...☺