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Topic: Stuck on HCL...  (Read 25305 times)

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dudeman

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Stuck on HCL...
« on: August 01, 2010, 03:06:06 AM »
My next experiment requires me to make my own HCL but I decided I want to scale it way down by 11.36 times.

I need to understand this...

Two liters of 20% HCL (12.1 mols) <--- experiment requires this

This is what I got after trying to learn molarity and stuff by myself... After I scaled it down by 11.36 times what I'm left with is....

170 ml 20% HCL (1.065 mols)

Is that correct? From my attempt at figuring this out I also think this means there is 3.883 grams of hydrogen chloride dissolved in a solution with water that equals 170 ml.

3.883 grams is having a hard time registering in my brain for some reason....

If I'm right... I should first dissolve the Hydrogen chloride into 150 ml of water and THEN add enough water to bring the total volume up to 170 ml... By doing this I will create 170 milliliters of hydrochloric acid with a concentration of 20% (1.065 mols)...

discodermolide

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Re: Stuck on HCL...
« Reply #1 on: August 01, 2010, 03:40:46 AM »
20% HCl = 20gHCl/100mL that is 400g in 2liters = 400/36.5 = 10.95M
scale it down by 11.36 times you have 0.965 mols of HCl in 176.05 mL
0.965mols of HCl = 35.22g. i.e. 35.22g in 176.05mL water .
a 20% solution
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Borek

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Re: Stuck on HCL...
« Reply #2 on: August 01, 2010, 07:45:23 AM »
20% HCl = 20gHCl/100mL

Assuming w/v, it can be w/w as well.

(1.065 mols)

Is that correct? From my attempt at figuring this out I also think this means there is 3.883 grams of hydrogen chloride

Molar mass of HCl is around 36.5 g/mol, without further analysis your mass seems to be ten times too low.
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nj_bartel

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Re: Stuck on HCL...
« Reply #3 on: August 01, 2010, 12:44:55 PM »
I don't think it's unreasonable to be suspicious of an experiment using 2L of acid, lol.  So what's your experiment here?

dudeman

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Re: Stuck on HCL...
« Reply #4 on: August 01, 2010, 03:02:35 PM »
I don't think it's unreasonable to be suspicious of an experiment using 2L of acid, lol.  So what's your experiment here?

nj_bartel    Can we stay on topic please?

20% HCl = 20gHCl/100mL

Assuming w/v, it can be w/w as well.

(1.065 mols)

Is that correct? From my attempt at figuring this out I also think this means there is 3.883 grams of hydrogen chloride

Molar mass of HCl is around 36.5 g/mol, without further analysis your mass seems to be ten times too low.

Thank you! ten times to low makes sense to me... That is where I was stuck... On my first attempt I found that 38.83 grams of HC would be needed for a 20% HCL (170ml total volume) solution but then I was unsure about that and tried again using a different method and came up with 3.883 and then I became really unsure.

So according to your calculations the amount of hydrogen chloride needed is going to be around 38.83? If that is right would you have any tips on how I would go about measuring out 38.83 grams of hydrogen chloride gas? Is there a way that I might be able to measure it in volume? How would I figure out the volume of HC in milliliters once in solution with H2O?

From my last post I was hassled about my lack of knowledge when it comes to HCL so I did some research..

HCL at 40% and above are not very stable at room temperature and at those percentages (40-60%) are considered fuming HCL. The highest concentration stable at room temperature and normal atmospheric pressure is 38% (from what I read)... So in order to make my 170ml 20% solution accurately without any special equipment I would first need to make a 38% solution and then dilute a portion of it to create a 20% solution.

Thanks again.

Borek

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Re: Stuck on HCL...
« Reply #5 on: August 01, 2010, 06:39:16 PM »
20% usually doesn't mean very accurate concentration, anything between 19-21 (or even 18-22) will do.

What is the concentration of the acid you have at hand?

Edit: nj question is not completely off topic, after all, we have some guidelines and forum rules. You have not broken them as of now, but we have to be vigilant
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dudeman

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Re: Stuck on HCL...
« Reply #6 on: August 02, 2010, 01:55:46 AM »
20% usually doesn't mean very accurate concentration, anything between 19-21 (or even 18-22) will do.

What is the concentration of the acid you have at hand?

Edit: nj question is not completely off topic, after all, we have some guidelines and forum rules. You have not broken them as of now, but we have to be vigilant

I understand how helping some people on here could be bad since they may be terrorists...

As of right now I have no acid. I found a lot of places to buy pure HCL online but I want to experience the chemistry first hand.

nj_bartel

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Re: Stuck on HCL...
« Reply #7 on: August 02, 2010, 02:12:46 AM »
Generally 2L isn't a good scale to "experience chemistry."  It's a good scale for a (very) amateur person dabbling around in chemistry to get a runaway reaction and boiling acid splashed on him.  Anyway, hydrochloric acid is used for a couple not so nice syntheses, so elaborate a little and maybe you can avoid some unnecessary danger.

Or scale your rxn down a lot.

dudeman

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Re: Stuck on HCL...
« Reply #8 on: August 02, 2010, 02:39:10 AM »
Generally 2L isn't a good scale to "experience chemistry."  It's a good scale for a (very) amateur person dabbling around in chemistry to get a runaway reaction and boiling acid splashed on him.  Anyway, hydrochloric acid is used for a couple not so nice syntheses, so elaborate a little and maybe you can avoid some unnecessary danger.

Or scale your rxn down a lot.

lame

nj_bartel

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Re: Stuck on HCL...
« Reply #9 on: August 02, 2010, 03:48:59 AM »
It's your body.  If you don't want people to advise you, or "can't" due to illicit reasons, at least isolate from everyone when you do it.

Borek

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Re: Stuck on HCL...
« Reply #10 on: August 02, 2010, 04:32:43 AM »
I found a lot of places to buy pure HCL online

Gaseous, compressed, in cylinders? Nobody sane will buy this stuff when they need a solution. Buy 38% solution and dilute.
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408

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Re: Stuck on HCL...
« Reply #11 on: August 03, 2010, 11:48:32 AM »
For the record, I am doing a rxn on 0.3mmol scale currently, and it is done in 400mL of boiling concentrated hydrochloric acid.  And it is not drug related at all.  It is just the solvent.

So, why not just dilute 37% HCl?

discodermolide

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Re: Stuck on HCL...
« Reply #12 on: August 03, 2010, 12:40:39 PM »
I found a lot of places to buy pure HCL online

Gaseous, compressed, in cylinders? Nobody sane will buy this stuff when they need a solution. Buy 38% solution and dilute.
This is crap, I used gaseous HCl all the time in my pilot plant with absolutely no problems. I used it to make solutions in ethyl acetate, ethanol etc.
From a cylinder it is easy to handle
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OC pro

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Re: Stuck on HCL...
« Reply #13 on: August 03, 2010, 01:32:00 PM »
@ Discodermolide: Don´t tell such stories to the newbies here. Gaseous HCl is very nasty stuff.  I have also experience with CO, SO2, ethylene, H2 of course and also phosgene, all in gas form. It´s always a pain...

nj_bartel

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Re: Stuck on HCL...
« Reply #14 on: August 03, 2010, 03:00:05 PM »
For the record, I am doing a rxn on 0.3mmol scale currently, and it is done in 400mL of boiling concentrated hydrochloric acid.  And it is not drug related at all.  It is just the solvent.

So, why not just dilute 37% HCl?

I know your chemistry background, and I know his (lack) of chemistry background.  From his first posts on here, his interest in the subject matter seemed innocent enough - the Li2CO3 synth.  This could even be an extension project building off of that.  But beyond the fact that there are some not so nice syntheses using HCl, for his own sake, if the synthesis is legit, he's best outlaying what he's planning on doing so we can guide him safely.  You probably have a nice fumehood for all that acid boiling off and a water shower if something goes wrong.  He almost certainly does not.