Concept Question Q7B 2009 Final

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JohnArthurReyes_1B
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Concept Question Q7B 2009 Final

Postby JohnArthurReyes_1B » Wed Dec 02, 2015 8:39 pm

How is autoprotolysis related to the concept that [H3O+]+[OH-]=14? The problem asks for the concentration of acetic acid when the autoprotolysis of water needs to be taken to account. All we're given is KA=10^-7 M

Chem_Mod
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Re: Concept Question Q7B 2009 Final

Postby Chem_Mod » Wed Dec 02, 2015 11:40 pm

Water undergoes autoprotolysis so in sol'n, it will generate [H3O+] and [OH-] ions. When you add in acetic acid, it can react with the OH- ions generated by water.

JuliaPark2H
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Re: Concept Question Q7B 2009 Final

Postby JuliaPark2H » Sun Dec 06, 2015 2:22 pm

This also confused me as well, but remember how autoprotolysis just refers to water's reaction within itself as an acid or a base-- losing or gaining a proton. Kw of neutral water is 10^-14, where [H+]=[OH-]=10^-7. If either [H+] or [OH-] concentration is off, I conceptualize that it triggers autoprotolysis. And since formic acid is an acid, any concentration that makes [H+] less than 10^-7 will bring in autoprotolysis. I hope my thought process is correct.


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