Acid/base Ek 1001 792 chem

[GRod18]

Which of the following influence the pH of an aqueous solution of a weak base?

1. Concentraion of the base
2. PKb of the base
3. volume of solution

Answer is 1 and 2.

EK answer was just that with the base and pkb you can find PH.

can anyone show me how this comes about? I would really appreciate it.

Thanks in advance.

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[Salient]

by way of example:

NH3 + H2O <----> NH4+ + OH-

Kb = [NH4+][OH-]/[NH3]

So if you know [NH3] and Kb, you can calculate [NH4+] and [OH-] (they are the same, unless one of them existed in significant quantity beforehand).

If you know [OH-], you know the pH.