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# Calculating pH from alkaline solution Watch

1. In alkaline solutions, the OH- concentration is known. The concentration of H+ can be deduced from the ionic product of water:

[H+][OH-] = 1.0 x 10-14 mol2dm6. [H+] = Kw/[OH-].

If [OH-] = 1.0M, [H+] = 1 x 10-14 M and the pH of the solution is 14.
If [OH-] = 0.1M, [H+] = 1 x 10-13 M and the pH of the solution is 13.
If [OH-] = 0.01M, [H+] = 1 x 10-12 M and the pH of the solution is 12.

This is my question? If the Alkaline solution was 0.02M then what is the pH?

a) If [OH-] = 0.02M
b) kw/0.02= [H+]
c) 1.0 x 10-14 /0.02 = 5x10-13
d) -log10[5x10-13] = 12.30
e) pH = 12.30

Is this correct?
2. pH = 14 - pOH

pOH = - log 0.02 = 1.699

pH = 14 - 1.699 = 12.30

Looks good to me

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Updated: December 8, 2010
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