Kw and H3O/OH concentrations

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Malia Shitabata 1F
Posts: 127
Joined: Sat Aug 17, 2019 12:17 am

Kw and H3O/OH concentrations

Postby Malia Shitabata 1F » Mon Jan 13, 2020 7:06 pm

For water, is [H3O+] always equal to [OH-]? Because in class Professor Lavelle was saying they're both 1.0x10^-7 which is why Kw is 1.0x10^-14, but the book also mentions the see saw behavior when there's more H3O+, OH- concentration will decrease.

Fiona Latifi 1A
Posts: 102
Joined: Sat Sep 14, 2019 12:16 am

Re: Kw and H3O/OH concentrations

Postby Fiona Latifi 1A » Mon Jan 13, 2020 7:12 pm

The concentration of H3O+ is equal to that of OH- when the pH of the solution is 7. When the solution is neutral, the concentration of acid and base essentially cancel one another out.

Emily Chirila 2E
Posts: 112
Joined: Sat Jul 20, 2019 12:16 am

Re: Kw and H3O/OH concentrations

Postby Emily Chirila 2E » Mon Jan 13, 2020 8:27 pm

They are inversely related. If one increases, the other decreases. That is why Kw is a constant. When they are equal, that means the solution is neutral.

Chris Tai 1B
Posts: 102
Joined: Sat Aug 24, 2019 12:16 am

Re: Kw and H3O/OH concentrations

Postby Chris Tai 1B » Mon Jan 13, 2020 10:31 pm

When the concentrations of H30+ and OH- are the same in a given water, they are quite small and equivalent at 10^-7 M each. This leads to a pH of 7, since -log(10^-7) is 7. The reason there exist these concentrations of H30+ and OH- is because due to chance, water may as an amphiprotic compound form brief new covalent bonds in a chemical reaction of autoprotolysis: 2H20 -> H30+ + OH-

805422680
Posts: 103
Joined: Sat Sep 14, 2019 12:16 am

Re: Kw and H3O/OH concentrations

Postby 805422680 » Mon Jan 13, 2020 11:34 pm

the Kw of water remains constant at a given temperature, although the concentrations of hydronium and hydroxide ions can vary. for example, in an acidic solution if [H3O+] is say 1.00 x 10^-2, then using the Kw, we can conclude that the [OH-] is 1.00 x 10^ -12.

Celine 1F
Posts: 120
Joined: Fri Aug 02, 2019 12:16 am

Re: Kw and H3O/OH concentrations

Postby Celine 1F » Tue Jan 14, 2020 9:20 am

When the pH of a solution is 7, that's when the concentrations of H3O and H+ are equal to one another.


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