March 29, 2024, 03:13:07 AM
Forum Rules: Read This Before Posting


Topic: can pH or pOH ever be zero or negative?  (Read 18839 times)

0 Members and 1 Guest are viewing this topic.

Offline Faisal

  • Regular Member
  • ***
  • Posts: 36
  • Mole Snacks: +0/-1
can pH or pOH ever be zero or negative?
« on: March 02, 2008, 03:16:23 PM »
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?

Offline Arkcon

  • Retired Staff
  • Sr. Member
  • *
  • Posts: 7367
  • Mole Snacks: +533/-147
Re: can pH or pOH ever be zero or negative?
« Reply #1 on: March 02, 2008, 03:24:46 PM »
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, 05:40:47 PM by Arkcon »
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline Yggdrasil

  • Retired Staff
  • Sr. Member
  • *
  • Posts: 3215
  • Mole Snacks: +485/-21
  • Gender: Male
  • Physical Biochemist
Re: can pH or pOH ever be zero or negative?
« Reply #2 on: March 02, 2008, 03:26:12 PM »
Yes, pH can be negative if [H+] > 1M.

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

Offline Faisal

  • Regular Member
  • ***
  • Posts: 36
  • Mole Snacks: +0/-1
Re: can pH or pOH ever be zero or negative?
« Reply #3 on: March 02, 2008, 03:52:06 PM »
ohk...Thank you very much

Sponsored Links