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Textbook clarification: weak acids and bases

Posted: Thu Jan 16, 2020 11:01 pm
by DHavo_1E
Hello,

Could someone explain what the textbook means when it says that a solution of a weak acid in water would have a very, very low concentration of OH- ions to maintain autoprotolysis equilibrium? Thank you!

Re: Textbook clarification: weak acids and bases

Posted: Thu Jan 16, 2020 11:07 pm
by AArmellini_1I
So because it is a very weak acid/base it only dissociates by a small concentration. Therefore, since your KA or B is [products] / [reactants] and only a small concentration will dissociate into the product, Ka or B is a very small number divided by a much bigger number which = a very small number :) So to add on, you only need a small concentration of OH- ions to maintain equilibrium.

Re: Textbook clarification: weak acids and bases

Posted: Sun Jan 19, 2020 9:42 pm
by DHavo_1E
AArmellini_1I wrote:So because it is a very weak acid/base it only dissociates by a small concentration. Therefore, since your KA or B is [products] / [reactants] and only a small concentration will dissociate into the product, Ka or B is a very small number divided by a much bigger number which = a very small number :) So to add on, you only need a small concentration of OH- ions to maintain equilibrium.



Hi,
This helped me understand a lot more thank you! Also, are the OH- ions the conjugate bases of water? Thank you!!

Re: Textbook clarification: weak acids and bases

Posted: Sun Jan 19, 2020 10:23 pm
by Rafsan Rana 1A
OH- are the conjugate base of water. However, if water reacts with an acid, wouldn't it act as a base thus it would have a conjugate acid of hydronium ions?