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Author Topic: can pH or pOH ever be zero or negative?  (Read 7745 times)

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Faisal

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can pH or pOH ever be zero or negative?
« on: March 02, 2008, 09:16:23 AM »

I was solving acid-base probs for my exam...I noticed in the answers "pH=-0.3"...which means pH can be negative.
But then there was a question where conc. of OH- was 1M.Therefore pOH=-log 1 which is 0.But in the answers it said "pOH=1 and pH=14"....how is that possible...isn't pH+pOH=14...1+14=15!!!
Any comments?
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Arkcon

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Re: can pH or pOH ever be zero or negative?
« Reply #1 on: March 02, 2008, 09:24:46 AM »

Wikipedia has a fair explanation for very low pH values, some as low as -3.5, or even -5.  See: http://en.wikipedia.org/wiki/PH#Explanation

Though I would like to see the problem you've been given that gives a pH of -0.3, you might have made an error, given that the explanation for superacids and superbases implies they are non-ideal.
« Last Edit: March 02, 2008, 11:40:47 AM by Arkcon »
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Yggdrasil

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Re: can pH or pOH ever be zero or negative?
« Reply #2 on: March 02, 2008, 09:26:12 AM »

Yes, pH can be negative if [H+] > 1M.

The second part is probably a typo.  If [OH-] = 1M, then pOH = 0 and pH = 14.
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Faisal

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Re: can pH or pOH ever be zero or negative?
« Reply #3 on: March 02, 2008, 09:52:06 AM »

ohk...Thank you very much
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