pH to pOH

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KMcFarland_2L
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pH to pOH

Postby KMcFarland_2L » Wed Dec 09, 2020 8:27 am

When given the pH of a solution, to get to the pOH I have been subtracting the pH from 14, and doing the same thing for going from pOH to pH. Is this the right method, and if so, why?

AnnaNovoselov1G
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Re: pH to pOH

Postby AnnaNovoselov1G » Wed Dec 09, 2020 8:52 am

Yes, this is correct. This is because the concentration of pH times the concentration of POH must equal to to the equilibrium constant for the ionization of water, which is 1.0 x 10^-14. If you take the log of both sides and simplify, you would get pH + pOH =14.
We use pH and pOH because representing the concentration in whole numbers is easier that always saying the concentration of H= is 2.3 x 10^-6 (which equals pH of 5.6) or something like that.

Heather Szeszulski 1I
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Re: pH to pOH

Postby Heather Szeszulski 1I » Wed Dec 09, 2020 10:14 am

what is pOH? i am a little confused

gabbi_r2C
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Re: pH to pOH

Postby gabbi_r2C » Wed Dec 09, 2020 10:21 am

I agree with the answer above in regards to the original question. pOH is basically pH (ie -log[H+]) but instead of focusing on H+ concentration, we focus on OH- concentration. So pH and pOH are complimentary in that way, and always add up to 14.

SelenaDahabreh1D
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Re: pH to pOH

Postby SelenaDahabreh1D » Wed Dec 09, 2020 10:25 am

Heather Szeszulski 1I wrote:what is pOH? i am a little confused

pOH is a measure of the concentration of the hydroxide ion [OH-].
Just know that [OH-}*[H+]=1.00*10^-14, and pOH+pH=14.00
Here is a site that explains it in more detail: https://courses.lumenlearning.com/chemi ... h-concept/

Emma Ide 2E
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Re: pH to pOH

Postby Emma Ide 2E » Wed Dec 09, 2020 10:33 am

Yes, just know that pH+pOH= 14, so you can rearrange the equation depending on what is given.

OwenSumter_2F
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Re: pH to pOH

Postby OwenSumter_2F » Wed Dec 09, 2020 10:44 am

Also make sure given any of the four components (pH, pOH, OH- levels, H+ levels) that you can get the other three, as seen in the Sapling homework for this week.

Rob Tsai 2F
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Re: pH to pOH

Postby Rob Tsai 2F » Wed Dec 09, 2020 2:57 pm

OwenSumter_3D wrote:Also make sure given any of the four components (pH, pOH, OH- levels, H+ levels) that you can get the other three, as seen in the Sapling homework for this week.


What do you mean by OH- and H+ levels? I haven't started the homework yet, but I'm assuming this means the concentration of H30+ and OH-? With those values, you would simply plug both into -log base 10 to get pH and pOH, respectively. If I'm wrong, could someone explain how to utilize these two values?

Ariel Guan 1H
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Re: pH to pOH

Postby Ariel Guan 1H » Thu Dec 10, 2020 7:42 pm

yea, just know that 14 = pH + pOH. Also, to find [H+] from pH, the equation is [H+] = 10^-pH, and for [OH-], [OH-] = 10^-pOH


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