wasban - 25-1-2005 at 11:19
Hi
I have a drum of H2So4 that i couldn't use more than 4 litters and I need now
some HCL and NaHSO4 so i thought of mixing it:
NaCl + H2SO4 = HCL + NaHSO4
If i mix one mole of H2SO4 with one NaCl :
Do I need to do any heating (if so when do i stope heating)?
What is the concentration of the HCl (if <30% how do i rise-up it to 30-38%)?
would the NaHSO4 precipitate and just filter them?
any pro to help appreciate it
wasban
vulture - 25-1-2005 at 13:45
How concentrated is your H2SO4?
If the concentration of your H2SO4 is above 30% you'll get copious amounts of HCl gas, nasty.
wasban - 25-1-2005 at 16:57
thanks vulture
the cons of H2so4 is 97% i think but i will check
thanks
wasban
wasban - 25-1-2005 at 17:06
vulture
yest, the concentration of sulfuric 98%
runlabrun - 25-1-2005 at 19:11
how many litres do you have?!?
Anyway... as for your question, addition of NaCl to the acid in 1:1 molar ratio will produce HCl and NaHSO4 however the HCl will come off as an
instantaneous burst of horrible acid gas, very nasty as vulture mentioned.... and as you may think, not very good for your health...
If you are serious about wanting the products take a few mL say 50mL, work out mole content and dilute to make it far less concentrated. Add the stoi
amount of NaCl to it...
Doing it this way with diluted acid will allow the water content to adsorb some of the HCl gas which can be boiled away with the water after your
finished... so you dont get the rush of acidic vapour (well reduce the amount of gas released anyway).
-rlr
wasban - 26-1-2005 at 10:06
runlabrun
thank you for you help (that is what i need), let say I just did the following distilling:
1- I pour 2 litters concentrated H2SO4 in a PVC carboy.
2- The cap of this carboy is like valve with 2" nose so immediately after adding the NaCl i will close it
3 all the HCl gas will be directed to a small water tank using rubber hose between the cap nose in one end and immersed in the water tank in the
second end
my question is what is the relation between HCl concentration and water volume in the tank (to get 30%-38% HCl how much water should be there ie 2
litters)
the above setup is based on no heat to the acid + salt mix
thanks
Mumbles - 26-1-2005 at 16:08
A quick calculation assuming 100% absorbtion and 100% entrance into the second water shows you need 3.5L for 38%. I would probably use about this
much. You will probably end up closer to 32% however due to some still remaining in the carboy, and not 100% absorbtion. The use of a bubbler will
greatly help.
bio2 - 26-1-2005 at 17:48
Man, you guys better be CAREFUL.
First of all adding all the stuff together at once is inviting disaster. If diluted there is no practical way to concentrate the aqueous HCl..
HCl forms the 20% azeotrope with water at 108deg (muriatic acid) and anyway the HCl will be almost gone wayyyyyyy before it gets to 100deg. at
atmospheric pressure.
Second of all, this reaction does not go to completion even on strong heating. Contrary to popular opinion you will also get more than 2 products.
The concentration depends on the temp.
and using iced water is needed to recover most of it etc. etc.
This is how you do it........ Slowly drip an excess of concentrated sulfuric onto well stirred, conc HCl moistened, fine grain NaCl.
Gas generation is controlled by addition rate and the excess is easy to determine when you do it, say 20% or so. Don't heat until it slows to a
crawl and then very slowly.
First make a little test batch so you don't get any surprises when scaled up. This can get away from you pretty easily as there is a delay of
sorts even depending on the stirring speed. It is possible to make about 5Kg HCl (gas) in a day with reasonably sized equipment. You will need a
decent stirrer in the salt if you want any hope of getting a decent yield.
I have a procedure somewhere if you are determined. Whenever attempting something new STUDY all the physical properties of all the precursors.
Don"t just start mixing shit together or one day you will be very sorry. 
Have fun and be SAFE 
runlabrun - 30-1-2005 at 03:33
98% H2SO4 in PVC carboy = not good....
Bio2's method sounds good, do that..
-rlr
unionised - 30-1-2005 at 04:50
You also need a "suck back" trap of some sort, or you risk getting water running back into the H2SO4 which isn't funny.
Synopsis - 30-1-2005 at 10:14
I don't get the point here... If you want concentrated aqueous HCl then buy it, it's cheap as hell. If you want HCl gas, drip your sulfuric
acid onto dry NaCl in a closed vessel with some outlet to bubble the gas produced into something else. It's easy as hell. Don't use table
salt, as you'll produce some HI which will contaminate your acid.
No heating is necessary, at least, in my experience. Although I never experienced it, suck back may happen and is probably very dangerous so put some
flask between your generator and your receiving flask to catch what might goes back.
The only thing you really need is ventilation. Else, you might finish the batch with chemically induced asthma as HCl gas is quite nasty.
Mumbles - 30-1-2005 at 18:55
Not all table salt has Na/KI in it. Only the iodised stuff. For instance we don't have iodised table salt because the person who does the
majority of the cooking doesn't need it. Having her thyroid removed has that effect. It is very easy to buy uniodised salt. I think kosher
salt in just plain. There is always halite rock salt if you want that.