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Topic: heating HCL  (Read 15076 times)

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Offline mufan

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heating HCL
« on: June 18, 2007, 02:59:47 PM »
If I am correct then I think that HCL is made by bubbling HCL gas through water.  If so, what is the effect of heating HCL?  Does the gas escape at a certain temperature...if so then what temp is this? 

We are doing a reaction in excess HCL and seeing vapors escape the condensor at 60 Deg C.  Can anybody explain this?

Offline Yggdrasil

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Re: heating HCL
« Reply #1 on: June 18, 2007, 04:08:50 PM »
HCl is a gas.  How does temperature affect the solubility of gasses?

Offline mufan

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Re: heating HCL
« Reply #2 on: June 18, 2007, 08:31:01 PM »
heat makes solids more soluble in solvent obviously but I didn't know if gases behaved the same.

Offline constant thinker

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Re: heating HCL
« Reply #3 on: June 18, 2007, 09:04:18 PM »
Gases behave just the opposite. They become less soluble at higher temperatures.

If you want to keep the hydrochloric acid in solution, just cool the reaction system if possible, or increase the pressure (Henry's law).
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Offline Borek

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Re: heating HCL
« Reply #4 on: June 19, 2007, 03:02:47 AM »
Note: HCl doesn't behave exactly the same way other dissolved gases do, as it fully disociates. Thus there is (almost) no dissolved HCl, only H+ and Cl- in the solution. Still, it has solubility limit at about 37% w/w (perhaps a little bit more, can't remember right now).
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Offline mufan

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Re: heating HCL
« Reply #5 on: June 19, 2007, 04:14:45 PM »
so can you reflux HCL without changing the concentration?

Offline Borek

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Re: heating HCL
« Reply #6 on: June 19, 2007, 06:20:46 PM »
If you need it highly concentrated it will go away.
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Offline AWK

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Re: heating HCL
« Reply #7 on: June 20, 2007, 01:15:46 AM »
HCl forms an azeotrope HCl-water  with constant boiling point about 106 C containung about 20 % HCl. Its means during boiling HCl over 20 % concentration you remove HCl with traces of water (fumes with water from air), then the azeotope distillates up to complete evaporating of solution. When you start with HCl below 20 % then you remove some water first with traces of HCl, then the azeotrope distillates.
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