Misr
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Chemistry Help!
1-The concentration of water,solid substances and precipates should not appear in the equilibrium constant equation Kc , why?I don't understand.Please
don't tell me that because their concentration remains constant whatever their quantities. because I have read these words tens of times and I don't
really understand them.
2-according to my text book " if the reactants and the products are in the gasoeus state,the concentration is expressed by their partial pressure"
What does this mean?
3-CH3COOH <----->CH3COO- + H3O+
let a be the no. of dissociated moles.So if we want to calculate the concentration of CH3COOH why should we say its remaining concentration=C-a,where
C is the orginal concentration of CH3COOH before dissociation????.
4-H2O <---->H+ + OH-
Kc= [H+] [OH-]/[H2O]=10^-14
Kw=[H+] [OH-] = 10^-14
how could the two equations have the same value?why we are totally neglecting water?and what is the importance of calculating Kw?
I've asked a question here here but it made no sense so please don't repeat the same answer.
http://answers.yahoo.com/question/index;_ylt=AiC7ZvT5Ou13Nfd...
5-In Ostwald law, sometimes we assume (a) as no. of dissociated moles, sometimes we assume (a) as degree of dissociation which equals no. of
dissociated moles/the total no. of moles of a substance before dissociation
http://www.pinkmonkey.com/studyguides/subjects/chem/chap12/c...
so, what is (a) ?
Help me please I'm very confused!
Thanks in advance.
Practice makes perfect
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madscientist
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Thread Moved
11-12-2010 at 04:14 |
kmno4
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Quote: Originally posted by Misr  | The concentration of water,solid substances and precipates should not appear in the equilibrium constant equation Kc , why?I don't understand (...)
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They can do appear, of course. But activities of pure substances are equal 1 (why ? -> by definition) and multiplication/division by "1" changes
nothing.
A little more you can find here:
http://en.wikipedia.org/wiki/Self-ionization_of_water
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