Chemical Forums
Chemistry Forums for Students => High School Chemistry Forum => Topic started by: kclive on October 07, 2005, 09:55:22 PM
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0.25 M CH3OH: find the concentrations of each ion or molecule present in the solution.
:please:
Since (in my knowledge), CH3OH does not dissociate in solution, this must be the final solution to the problem. How do you do this?!! :swear: All help is appreciated.
-kclive
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YEs sounds right concentration of CH3OH is 0.25M.
Unless you know K or pKa and it is forming the CH3O- ion? doubt it though, strange question huh?
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Ka of methanol is too low for CH3OH dissociation to be of any concern here, however, don't forget about water autodissociation.
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What do you by K, Ka, and pKa of CH3OH? Seems like I will be learning this later this year. But can you please simply tell me how CH3OH dissociates without using any super-advanced science terms?:aak:
But you said there is a such thing as a CH3O- ion. It's probably not on my humongous ion chart I have here. So that means that CH3OH will dissociate into CH3O- and H+ ions in solution. Voila!
:D
Thanks for all of your help.
-kclive
:cool1:
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pKa for methanol is somewhat close to water and is exactly 15.2.. so there will be ions in the solution through dissociation..
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pKa for methanol is somewhat close to water and is exactly 15.2.. so there will be ions in the solution through dissociation..
Can you give reference? I remembered it as about 17, but I could be wrong and I can't locate it in my books at the moment (although I am almost sure it is less then 10 feets from me ;) )
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15.2 is in a table I have at home
I found a table on google, and it says 15.5 in it. Click here. (http://64.233.183.104/search?q=cache:CY_59WBxjl4J:www.crab.rutgers.edu/~alroche/Ch10.doc+pKa+methanol&hl=pl&client=firefox-a)
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If they haven't yet learned about Ka etc then I don't think they'd be asked to find how methaol and water dissociate to form the three ions.
I don't suppose it's an easy calculation, although I might be wrong. My initial reserverations come from the fact that the H+ ion would be shared and change the Ka for both of them...Am I wrong in this?
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I don't suppose it's an easy calculation, although I might be wrong. My initial reserverations come from the fact that the H+ ion would be shared and change the Ka for both of them...Am I wrong in this?
No, it is not trivial calculation. And yes, you are wrong - Ka will be not changed ;)
However, I will be not surprised if the correct (expected) answer will be H2O, CH3OH and water dissociation products (H+ and OH-). Water ionization is covered together with pH, so not very late in the chemistry course.