[OH-] and pOH difference

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Daniela Santana 2L
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Joined: Wed Sep 30, 2020 9:59 pm

[OH-] and pOH difference

Postby Daniela Santana 2L » Sat Dec 12, 2020 4:20 am

What is the difference between [OH-] and pOH? Question 5 on sapling asks for us to list both but I thought that they meant the same thing, are we supposed to put the same thing for both of them on Sapling or are they different. Could someone clarify what the difference between the two are?

Jason Nguyen_1B
Posts: 51
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Re: [OH-] and pOH difference

Postby Jason Nguyen_1B » Sat Dec 12, 2020 4:41 am

[OH-] and pOH aren't the same thing but they're related. The difference between the two is that [OH-] represents the concentration of [OH-] or the molarity of OH-. It basically represents the concentration of OH- that is produced when a strong base reacts with water for example. pOH is a value that represents the basicity of a solution. They're related because in order to find pOH, you take the -log[OH-]. I hope that helps!

Jiwon_Chae_3L
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Re: [OH-] and pOH difference

Postby Jiwon_Chae_3L » Sat Dec 12, 2020 4:58 am

[OH-] is the concentration/molarity of OH- while pOH is the counterpart to pH, thus representing the alkalinity of a solution. And pH and pOH are related by the equation pH + pOH = 14

FrancescaHawkins2H
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Re: [OH-] and pOH difference

Postby FrancescaHawkins2H » Sat Dec 12, 2020 8:45 am

My understanding is that pH refers to the concentration of H, or more specifically the concentration of H3O+, whereas pOH is the concentration of OH-. To calculate pH, use pH =-log [H3O+] and to calculate pOH, use pOH = -log [OH-]. To if given one and asked to calculate the other, you should be able to subtract from 14 because of the relationship stated above where pH + pOH = 14.

Kelly Tran 1J
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Re: [OH-] and pOH difference

Postby Kelly Tran 1J » Sat Dec 12, 2020 4:08 pm

[OH-] is the concentration of hydroxide ions (OH-) whereas pOH is the -log of [OH-]. In other words, pOH is a value that indicates how basic the solution is.

Brandon Le 3C
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Re: [OH-] and pOH difference

Postby Brandon Le 3C » Sat Dec 12, 2020 4:13 pm

Similar to how pH is not the same as [H3O+] (the concentration of H3O+), pOH is not the same as [OH-]. Like previous users states, pOH = -log[OH-], and [OH-] = 10^-pOH. I believe Dr. Lavelle stated in the lecture that the pH and pOH scale are simply easier methods of describing the concentration of H3O+ and OH-, respectively, in the solution. So instead of saying the solution has an OH- concentration of 1.0 x 10^-8, we would say the pOH is 8 (or the pH is 6). It's just used to make things easier to describe.

LovepreetSran_3H
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Re: [OH-] and pOH difference

Postby LovepreetSran_3H » Sat Dec 12, 2020 4:31 pm

[OH-] is the concentration of OH- whereas pOH is the basicity of the solution. We use -log[OH-] to find the pOH. To find the [OH-] we use 10^-pOH.

Joey_Okumura_1E
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Re: [OH-] and pOH difference

Postby Joey_Okumura_1E » Sat Dec 12, 2020 4:38 pm

[OH-] is the concentration of OH- ions while pOH is a measure of the basicity of a solution. (It is similar to how [H+] is the concentration of H+ ions while pH is a measure of the acidity of a solution.) pOH = -log([OH-] )

Jerry_T
Posts: 89
Joined: Wed Sep 30, 2020 9:46 pm

Re: [OH-] and pOH difference

Postby Jerry_T » Tue Dec 15, 2020 10:47 pm

The relationship between [OH-] and pOH is the same as the relationship between [H+] and pH. We use the logarithmic value (p- prefix) for convenience.
pOH = -log[OH-]
[OH-] = 10-pOH
You might find this image useful.
Image

Nan_Guan_1L
Posts: 84
Joined: Wed Sep 30, 2020 9:59 pm

Re: [OH-] and pOH difference

Postby Nan_Guan_1L » Wed Dec 16, 2020 6:02 am

[OH-] is the concentration of OH- ions in the solution. pOH represents how alkaline a solution is. Mathematically, we can get pOH by calculating -log [OH-].


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