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Another question, about buffer solutions, where I'm very confused at what to do

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RaelAerosolKid:
So my teacher gave us an exercise list and one of the questions (translated) was this:

"A solution (A) contains an alkaline mixture of Na2X 0.2000M [H2X (pKa1 = 5.5) and HX-
(pKa2 = 11.0)] and 0.2500 M NaY [HY (pKa1 = 11.0)].
A 10.00 mL aliquot of solution (A) was titrated against 0.2000 M HCl solution.

What volume of 1.5000 M HCl solution should be added to 2.00 L of solution (A) for
to obtain a buffer solution pH = 7.0?"

I was taught how to calculate the volume when I had a simple weak acid and salt, not this mess.

I thought about giving priority to the strongest acid, or to the first Ka, or the most concentrated salt but I never came to a solid conclusion. I have searched "buffer solution with mixture of 2 weak acid salts" and found nothing.

Is this question even solvable? xD

Thanks in advance

AWK:

--- Quote ---I was taught how to calculate the volume when I had a simple weak acid and salt, not this mess.

--- End quote ---
Calculate it independently for both salts and add the volumes of acid.

--- Quote ---What volume of 1.5000 M HCl solution should be added to 2.00 L of solution (A) for to obtain a buffer solution pH = 7.0?"

--- End quote ---
Frankly saying, chemists will not consider this solution after neutralization as a buffer solution. But roughly you can think of it as a buffer solution based on the acid dissociation constant Ka1.

RaelAerosolKid:
Don't know if this is against the rules, but could you be more direct in how to solve this question?

The first part makes total sense, thanks.

But when I think about the Henderson–Hasselbalch equation to find the pH,
(it would be "pH = Pka1 - log(([H2X] + moles of HCl)/([HX-] - moles of HCl))", right?)
 I don't know the concentration of [H2X] or [HX-] to begin with so therefore I also wouldn't know what amount of HCl to add

Am I missing something? Damn this subject is hard

RaelAerosolKid:
Oh I think I have a clue, I just have to calculate the pH of the salt solution alone and then I think there is no need to do the Henderson–Hasselbalch equation.

So I would have, say, X2- from the salt + H2O -> HX- + OH-

That means I would have to use the Ka2 to then transform it into a Kb and then find the concentration

Is this correct?

AWK:
Solve for buffer H2X/NaHX with the sum of the concentration 0.2000 M, then neutralize all salts with HCl.

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