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Topic: Can a solution be both pH 7 and acidic?  (Read 3796 times)

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mpellow

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Can a solution be both pH 7 and acidic?
« on: September 11, 2005, 11:01:35 AM »
This question seems counterintutitive to me: my understanding is that a pH 7 solution is, by definition, not acidic. However, I recently saw a discussion in a textbook that mentioned pH7, acidic conditions.  Is there any way a solution can be both pH 7 and (Bronsted-Lowry) acidic?  (Of course Lewis acids might be in solution, but I'm pretty sure this wasn't the sense of the textbook's discussion.)

Thanks!

Offline Mitch

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Re:Can a solution be both pH 7 and acidic?
« Reply #1 on: September 11, 2005, 05:40:32 PM »
A soultion at pH7 is neutral like you suspect. I'm guessing you saw the pKa of an acid above 7 and are getting yourself confused. If not, let us know.
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dpsguy

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Re:Can a solution be both pH 7 and acidic?
« Reply #2 on: September 13, 2005, 02:20:05 AM »
pH is not an accurate indicator of acidity.Eg.at low temperature,water(ice) has pH <7.But it is still neutral.

Offline AWK

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Re:Can a solution be both pH 7 and acidic?
« Reply #3 on: September 13, 2005, 03:04:21 AM »
It depends on what we accept as ideal neutrality - pH of ideal pure water or [H3O+ ]=10-7.
pH of pure water depends on temperature; in 23 C pH=7,  at higher temperature is slightly less than 7, and at lower temperature is slightly higher than 7.
« Last Edit: September 13, 2005, 03:50:42 AM by AWK »
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