# Homework Help: Writing a physics report about hydrochloricacid

1. Dec 13, 2004

### Cr4X

I am writing a physicsreport about hydrochloricacid, but I have a quick question, and I don't have time to ask my teacher so I hope you can help me.

I am making hydrochloricacid from NaCl and $$NaHSO_4$$, then I get HCl and $$Na_2 SO_4$$, and when let the HCl get in contact with water it becomes acid. My question is, can you then make 100% (or 99% if you want) hydrochloricacid by adding 470 times more HCl as water or is the HCl somehow not as strong as if you had done it other ways?

I know this may sound incredible stupid, but I want to be 100% that my answer is correct.

2. Dec 13, 2004

### Cr4X

If that is correct then what I am being thought is wrong (which shouldn't really suprise me that much, although what I have been taught here made sence). Let me try explaining this again.
We were warming it up, so that:

$$NaCl + NaHSO_4 > HCl + Na_2 SO_4$$

If I didn't make HCl what the **** was that gas making me cough then?

3. Dec 14, 2004

### primarygun

What does 100% refer to?
The molarity or..?
Hydrogen chloride is not extremely soluble as hydrogen iodine in water.
There is a limit of decomposition of HCl. After that any HCl gas put in stay in form of gas in the water as it can't dissolve.

4. Dec 14, 2004

### Cr4X

100% refers to how concentrated the acid is. Like you can have 2M acid. 100% is simply the most concentrated hydrochloricacid you can get (that is 470 times more HCl than water).

My question is if it is possible to make 100% concentrated hydrochlrocicacid by just adding 470 times more HCl than water, no matter how the HCl was created?

5. Dec 14, 2004

### Nylex

"Hydrochloric acid" is two words!

6. Dec 14, 2004

### Cr4X

Oh sorry, english isn't my primary language... but I gotta admit it was pretty hard to spell in one word :)

7. Dec 14, 2004

### dextercioby

Well,your reaction is not gonna go that easily,since the poor choise of reactants.Note that the ion $HSO_{4}^{-}$ has a smaller acid constant (is a weaker acid) when it loses a proton,than the neutral $H_{2}SO_{4}$ losing a proton.So my,guess is that u get more HCl by puttin' sulphuric acid over a salt of the hydrochloric acid,and to prove it,cf.
$$NaCl+NaHSO_{4}\rightarrow Na_{2}SO_{4} +HCl$$
$$2NaCl+H_{2}SO_{4} \rightarrow Na_{2}SO_{4} +2HCl$$

Daniel.

Last edited: Dec 14, 2004
8. Dec 16, 2004

### Cr4X

That is true, and I have mentioned that way in my report as well, but we are currently not allowed to make it from sulphuric acid, as it is too dangerus for some reason.
Anyway, thanks for your help just wanted to be sure that what I wrote was correct.