Difficult pH chemistry problem?

Posted on 2016-03-26 14:44:00 in Chemistry by ENCHO

We'll denote the citric acid by H3Cit. The citric acid is a weak triprotic acid with chemical formula C3H4(OH)(COOH)3 (but the formula is not important for the purposes of the problem). 

Calculate the pH of aqueous solution of disodium citrate (Na2HCit) with molar concentration 0,01mol/L. You are given the dissociation constants of citric acid : 
Ka1 = 7,4 * 10^-4 
Ka2 = 1,7 * 10^-5 
Ka3 = 4,0 * 10^-7 
In your solution consider the equilibrium of : 
1) Dissociation 
2) Hydrolysis 
3) Autoprotolysis of HCit(2-) (ampholyte) 
Preferably consider the reaction with the greatest equilibrium constant. 

Bonus question : Will the pH of the solution change if it is diluted 10 times.

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