Sciencemadness Discussion Board

Diluting Muriatic

demax - 3-2-2008 at 17:57

Hi all,

what is the best way to dilute a 37% solutin of muriatic to a 10% solution?

Simply add more dh2o to the muriatic tilll the desired % is reached.

Something about azeotropes????

-Dmax

microcosmicus - 3-2-2008 at 18:18

Azeotropes have to do with boiling and distillation, not dissolving and diluting --- an
azeotrope is a mixture which has a single boiling point just like a pure substance and
hence its concentration is unaffected by distillation. To dilute, Just mix the appropriate
amount of 37% acid with te appropriate amount of water to obtain the 10% concentration.

When mixing acid, be careful --- as a rule, it is best to add the acid to the water,
not the other way around. This keeps the concentration of the acid low during the
process of mixing and helps dissipate the heat generated. While this point is not
as crucial with HCl with H2SO4, it is nonetheless good safety practice to get into
habit of always adding acid to water.

BromicAcid - 3-2-2008 at 19:41

Use what microcosmicus said as a guide. For a quick calculation of how much liquid you have to add use the following equation:

M<sub>(i)</sub>V<sub>(i)</sub> = M<sub>(f)</sub>V<sub>(f)</sub>

In this equation you have your M which is your molarity (or for you, your percent concentration) and your V which is your volume. The subscript i's stand for your initial and the subscript f's stand for your final. So, for example, you want 100 ml of your final 10% solution so you plug in the numbers...

(0.37)V<sub>(i)</sub> = (0.10)(100)
(0.37)V<sub>(i)</sub> = 10
V<sub>(i)</sub> = 27.027

That final number is the number of milliliters of your initial 37% solution that you would have to dilute down to 100 milliliters total. If you just add 73 milliliters of water you will end up with a close amount though not right on the money because the density will change and your final volume will be a little off. Normally where accuracy is very important a volumetric flask is utilized.

demax - 4-2-2008 at 01:57

Yes just a simple formula like this should do the trick.

Having a closer look at another bottle of muriatic it says 30g/L HCL so if 200 mls of this is to be reduced to a 10% solution the follwing eaquation is carried out;'

(0.30)V(i)=(0.10)(200)
(0.30)V(i)=20
V(i)=20/.30
V(i)=54

Thus to 200ml of this muriatic is added to 54 ml of water???


thanks,

Demax

BromicAcid - 4-2-2008 at 17:41

Nope, what you calculated is the initial volume, and you calculated it with your 30g/L HCl so that is the amount of your HCl solution that you want to start out with. So you would take 54 ml of this solution and dilute it to 200 ml total (which is the final volume that you used in the equation, it's what you were going for). Or like I said you could just add 146 ml of water to your 54 ml of HCl solution to end up with your final volume in that equation of 200 ml of your 10 g/L solution.

shadow - 5-2-2008 at 04:59

What if a procedure asks for ethereal hcl?

"The resulting oil was dissolved into 500 ml of dry diethyl ether and the hydrochloride salts were made with ethereal HCl. "

This is a little too vague for me.

shadeoux

bio2 - 5-2-2008 at 14:06

Either HCl gas or aqueous HCl is added to the "oil in ether" or prepared and added separately.

shadow - 6-2-2008 at 04:39

It's the aqueous HCL porportions that I wouldn't know to mix.
Are there any set porportions?
I have some 37%. How much water am I adding?'
Thanks ahead,
shadoo

bio2 - 6-2-2008 at 17:36

.....hydrochloride salts were made with ethereal HCl. "......

Use 150% of the molar amount of base you are converting to the HCl salt.

Don't add water as the water in the acid will not mix with ether anyway and not
all of the HCl will partition to the ether. The water should likely be separated
depending on the mix of reactants and the ether will absorb some water which
may redissolve the HCl salts if this is a problem to what you are trying to achieve.

Better is to bubble the HCl gas into the ether.

syntelman - 9-2-2008 at 08:15

Ethereal HCl is commercially available, but very expensive (on a molar basis).
Gasous HCl is not the most fun thing to have around as it corrodes almost everything very fast, and should really not be used outside a fume hood (or outside on a windy day) if you like your lungs. It is easy to generate thoughso if you have the possibility to do it in a well ventilated area gas a larger volume of ether and save it for later. There has been some discussions of it's stabilitiy but I think the consensus was that it is stable enough to store for months.

Also depending on what compound you are salting HCl in isopropanol may work, commercially available dirt cheap as a 5-6N solution. Some product may dissolve but often works good enough if you put the solution in the freezer overnight.

Or carefully mix acetyl chloride with (m)ethanol and get a HCl solution in (m)ethyl acetate

stoichiometry of ethereal HCl

chemrox - 15-11-2008 at 21:36

Does anyone know how much HCl should be in "ethereal HCl"? And if so how to get to that point?

smuv - 15-11-2008 at 22:22

Quote:
Originally posted by bio2
Don't add water as the water in the acid will not mix with ether anyway and not
all of the HCl will partition to the ether. The water should likely be separated
depending on the mix of reactants and the ether will absorb some water which
may redissolve the HCl salts if this is a problem to what you are trying to achieve.

Better is to bubble the HCl gas into the ether.


Actually ether is soluble in concentrated mineral acids. With acids stronger than hydrochloric the ether is decomposed (ex. sulfuric and hydroiodic) but solutions of ether in concentrated HCl are fairly stable.

The reason for the solubility of ether in conc. HCl is the formation of an etherate ([R2OH]+) which is much more polar than an ether. Luckily the chloride ion is not nucleophilic enough to destroy this etherate to form ethyl chloride and ethanol. Bisulfate, bromide and iodide anions on the other hand ARE nucleophilic enough to decompose etherates.

[Edited on 11-16-2008 by smuv]

chemrox - 16-11-2008 at 13:37

@Smuv- are you saying the way to get 6M ethereal HCl is add the requisite amount of 37% aqueous HCl to ether? What if you're making a highly water soluble salt? The kind where the general procedure is to dissolve the base in ether/acetone and bubble HCl through it?

Could you titrate ethereal HCl with alcoholic KOH and use methyl orange in toluene as the indicator?

smuv - 16-11-2008 at 13:50

No I was correcting bio2, by point out that concentrated HCl will dissolve quite a lot of ether and vice versa.

Is methyl orange soluble in toluene? I would give an ethereal solution of phenolphthalein a try for that titration. I have no experience with this however.