interlanken-fall
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in doing calculations why do people use
Ka= [H+][OH-]/ [HA]
shouldn't if be
Ka = [H+]^2/ [HA]
why do they use the top formula ?
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scotty74
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pretty sure the bottom can only be used when dealing with weak acid calculations, for buffers you cant assume [H+]=[A-]] or something along those lines
Last edited by scotty74; 1 month ago
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Pigster
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(Original post by interlanken-fall)
in doing calculations why do people use
Ka= [H+][OH-]/ [HA]
shouldn't if be
Ka = [H+]^2/ [HA]
why do they use the top formula ?
I hope you mean Ka= [H+][A-]/ [HA] instead of Ka= [H+][OH-]/ [HA].

Ka = [H+]^2/ [HA] can be used if all you have is a weak acid solution, since [H+] = [A-] after all, the only way you you can make a H+ means also making an A- (HA <-> H+ + A-)

Ka= [H+][A-]/ [HA] is used when dealing with buffer solutions, where [A-] can be different to [H+], either by partly neutralising a weak acid, and/or by adding a salt of that weak acid.
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