What is the pH after adding a base?

[megzb]

This is my question:
When a 17.9 mL sample of a 0.493 M aqueous nitrous acid solution is titrated with a 0.476 M aqueous barium hydroxide solution, what is the pH after 13.9 mL of barium hydroxide have been added?
I'm not really sure how to start it?
I have the moles of the acids and the base.
[acid]=8.8247E-3
[base]=6.6164E-3
but after that I'm lost! Help would be greatly appreciated!

 

[Borek]

Classic buffer question. Assume neutralization went to completion, calculate concentrations of acid and conjugate base, use Henderson-Hasselbalch equation.

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[megzb]

And how do I find the concentrations exactly?

Classic buffer question. Assume neutralization went to completion, calculate concentrations of acid and conjugate base, use Henderson-Hasselbalch equation.

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buffer calculator, concentration calculator
pH calculator, stoichiometry calculator

 

[Borek]

Stoichiometry. You start with some amount of nitrous acid. You add some base. If neutralization went to completion, you are able to easily calculate amount of the acid left, and amount of conjugate base (product of the reaction) - this is just a limiting reagent question. You know amounts, you know the final volume - just plug and chug.

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methods

 

[Biophreak]

The molarity of your acid/base is given. Molarity = Moles/Liter IS your concentration.

 

[Borek]

Note: in case base is in excess all acid was neutralized, and it is just a limiting reagent question.

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