Hi Axel,

I am afraid you have not seen a plant yet vertically.

I'm a little bit jealous that you do not have a problem with the reagent prices - it is very nice for you ...

Without the completeness here I outline some aspects. But, first of all, it is not about the good or bad industry. It is not about the business managers who are able to sell even their mother to realize 5 cent/kg profit. Please, calculate what is the profit if you can spare 5 cent/kg in a 1 M ton/year production (50 M USD/EUR as you like it). Even not about the pr guys who are able to press you what you are not really want.

It is simple economy. The physics (and the chemistry, in one word: the science) also costs. Costs a lot. Do you know how much is to evaporate 1 kg water? And usually the amount is not 1 kg ...

The scientific reasons are in the textbooks what I recommended - and I do not want to spare the efforts to read them (easily received information is volatile!) , but please, think also about the followings:

- The producers are producing what has demands using an optimized quality (this is the only one point where the science should be taken into consideration), size, and amount. The storage is money, the packaging material is money and the analysis of the product (QA/QC costs) is also money.

- Let's see a 1M ton/year production of HCl plant: if they want to produce ~20% HCl instead of ~37 the storage capacity should be also doubled, the package materials - independently from barrels to bottles - should be doubled. Does it worth it? Particularly when most user prefers the cc version because of the flexibility. So it is a demand.

Of course, you can buy even ~10% HCl for household purposes but for this product the market is considerably smaller. But, additionally, the HCl for the public is more expensive than for the industry.

- Or, you can also calculate the profit of the producer/distributor when you buy 1 N HCl instead of cc (~12.5 N) HCl. This is only an example. In the price list of a big supplier 100 ml cc. HCl which is equivalent ~ 1.3 L (=13 bottles). 100 ml 1 N HCl is 29.25 EUR but 100 ml cc HCl is only 40.50 EUR, or almost the same quality, 1 L=21.00 EUR (calculating for 1N HCl your cost is 13*29.5=380.25 EUR, or 13 L=130*29.25=3802.5 EUR). I neglected the bottle prices.

Due to technical reasons the producers are supplying their products in the most demanded concentration, largest amounts, and the lowest purity. And although the best thing is to sell the water in the price of gold one crucial problem is the volume.

Please, also think about why the quality criteria are so large. Sticking on the example: could you recognize if the cc HCl is not 38% only 36.5%? I am not sure but I am know that if there are more demand than the available for the cc you will get the somehow less concentrated one. Of course, I know that there are analytical limitations also but think in cubic meters and not ml on L scale.

It is a naive thing to believe that first thing for a producer is the charity. They are producing what the largest consumers want - until it produces profit for them. If not, they cease production without any conscience.

First, you should google before asking.

Second, common inorganic acids are not manufactured in water.

Third, there is no a single answer to your question.

Fourth you can have aqueous solutions of all acids with the same (commonly low) concentrations in water by dilution.

Google will help you

Hi Sachin,

the answer is simple: the money governing the manufacturing.

Scientific explanations can be found chemical technology text/handbooks,

like

Andreas Jess, Udo Kragl, Peter Wasserscheid: Chemical Technology: An Integral Textbook, Wiley-WCH; or

G. N. Pandey: Textbook of Chemical Technology Vol-1 2/e, Vikas Publishing (btw this is an Indian specific book).

It seems that although google is your friend but Yurii is not :)

well, HCl is a gas, so if you want pure you can find in pressurized cylinder, the 37% is in water, I think is the saturated water solution, the same for HBr, H2SO4 is almost pure 98% is liquid itself.

Dear Dr. Geletti,

Many thanks for your response.

Sir, I am not a frequent user of RG rather often use GOOGLE. But, I believe RG is helpful too for a technical query.

Anyway Dr. Jicsinszky's and Dr. Mollica's answers seems helpful.

Once again heartfelt thanks to all.

Usually it is not MONEY or THE BAD INDUSTRY that governs the acid content of the standard mineral acids. In most cases it is PHYSICS and it is called azeotrops or related meaning that you cannot distill these acids to a higher acid content by distilling the water off. :-).

In other cases it is feasibility: we in academia are not the most important users of these acids (!), it is the manufacuring sector (producing dyes, polymers, coatings, fertilisers, pharmaceuticals ...). The companies produce what these customers want (of course!).

Hi Axel,

I am afraid you have not seen a plant yet vertically.

I'm a little bit jealous that you do not have a problem with the reagent prices - it is very nice for you ...

Without the completeness here I outline some aspects. But, first of all, it is not about the good or bad industry. It is not about the business managers who are able to sell even their mother to realize 5 cent/kg profit. Please, calculate what is the profit if you can spare 5 cent/kg in a 1 M ton/year production (50 M USD/EUR as you like it). Even not about the pr guys who are able to press you what you are not really want.

It is simple economy. The physics (and the chemistry, in one word: the science) also costs. Costs a lot. Do you know how much is to evaporate 1 kg water? And usually the amount is not 1 kg ...

The scientific reasons are in the textbooks what I recommended - and I do not want to spare the efforts to read them (easily received information is volatile!) , but please, think also about the followings:

- The producers are producing what has demands using an optimized quality (this is the only one point where the science should be taken into consideration), size, and amount. The storage is money, the packaging material is money and the analysis of the product (QA/QC costs) is also money.

- Let's see a 1M ton/year production of HCl plant: if they want to produce ~20% HCl instead of ~37 the storage capacity should be also doubled, the package materials - independently from barrels to bottles - should be doubled. Does it worth it? Particularly when most user prefers the cc version because of the flexibility. So it is a demand.

Of course, you can buy even ~10% HCl for household purposes but for this product the market is considerably smaller. But, additionally, the HCl for the public is more expensive than for the industry.

- Or, you can also calculate the profit of the producer/distributor when you buy 1 N HCl instead of cc (~12.5 N) HCl. This is only an example. In the price list of a big supplier 100 ml cc. HCl which is equivalent ~ 1.3 L (=13 bottles). 100 ml 1 N HCl is 29.25 EUR but 100 ml cc HCl is only 40.50 EUR, or almost the same quality, 1 L=21.00 EUR (calculating for 1N HCl your cost is 13*29.5=380.25 EUR, or 13 L=130*29.25=3802.5 EUR). I neglected the bottle prices.

Due to technical reasons the producers are supplying their products in the most demanded concentration, largest amounts, and the lowest purity. And although the best thing is to sell the water in the price of gold one crucial problem is the volume.

Please, also think about why the quality criteria are so large. Sticking on the example: could you recognize if the cc HCl is not 38% only 36.5%? I am not sure but I am know that if there are more demand than the available for the cc you will get the somehow less concentrated one. Of course, I know that there are analytical limitations also but think in cubic meters and not ml on L scale.

It is a naive thing to believe that first thing for a producer is the charity. They are producing what the largest consumers want - until it produces profit for them. If not, they cease production without any conscience.

Dear Laszlo and Axel,

I recommended all your answers. You are both right and not right

Laszlo, yours " the money governing the manufacturing." Mine, not only the money governs the manufacturing but also physics and chemistry behind the manufacturing.

Axel, yours " you cannot distill these acids to a higher acid content by distilling the water off ." Mine, the mentioned acids are manufactured by dissolving gases (HCl, HBr, SO3) in water, no distillation.

The strength of commercial aqueous acid solutions is controlled by numerous factors such chemistry/physics, safety, economics, etc.

Back to the original question. HCl is a gas, 37% is the saturated solution at room temperature. HCl is volatile and commonly the commercial solutions have lower strength. SO3( precursor of sulfuric acid ) is soluble in H2SO4, therefore you can get the formal strength of H2SO4 higher than 100%. There is no demand on the market of acid solutions with the same concentrations. The manufactures produce the most profitable products.

Thanks to all for the valuable responses.

I will just add that you should consider stability. For example, you should consider whether H2SO4 at 98% is more or less corrosive than at 30%...