Given Kw

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Given Kw

Postby CaminaB_1D » Sun Jan 20, 2019 2:12 pm

Can anyone explain the reasoning behind, given a Kw (at any temperature, doesn't really matter), why do we know that the concentrations of [H30+] and [OH-] the same?

Harshita Talkad 4L
Posts: 45
Joined: Thu Sep 27, 2018 11:16 pm

Re: Given Kw

Postby Harshita Talkad 4L » Sun Jan 20, 2019 2:19 pm

Since water is neutral, the concentration of H3O+ ions and OH- ions has to be equal, and since water is neutral at any temperature, Kw has to be the same.

Amar Singh
Posts: 16
Joined: Thu Sep 27, 2018 11:20 pm

Re: Given Kw

Postby Amar Singh » Sun Jan 20, 2019 3:17 pm

The concentrations of [H3O+] and [OH-] are equal because for water at any temperature, the only molecule you are starting off with is [H2O]. If one of the hydrogens from [H2O] leaves the original molecule and joins another [H2O] molecule, the new molecule becomes [H3O+] and the old one becomes [OH-]. This means that the hydroxide and hydronium ions must be created in equal quantities, meaning that they must be present in equal amounts in the solution.

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