Quick dissociation question, actually more of a math question.

[deleted74029]

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I know that with a weak concentration of acid or base in an aqueous solution the dissociation of water can affect the perceived pH. But I'm having trouble with the equation used.

If you have a 1x10-8 M solution of HCl, the percieved pH would be 8 but knowing thats not true cause its an acid you can use this equation to find out the real pH.

Kw = (x + 1x10-8)(x) = 1 x 10-14 with x being [H+] or [OH-]

x = 9.5 x 10-8 M but I can't figure out for the life of me how to do the calculation to get x. Any help?

 

[not respect]

Quadratic equation, or you can approximate, those would probably be the fastest.