[sharbeldam]

I did A.

But about B:
I did calculate the moles of acid -> 0.01 moles of H+

I have 0.5L of my buffer (NaHSO4)

Can someone give me a hint of where to begin? I Did solve a few questions regarding finding out how much acid or base to add to buffer to get to a specific pH but this is different.

[Borek]

Assume protonation of sulfate is quantitative and follow the stoichiometry.

[sharbeldam]

but do i just assume at first, like for instance make a buffer with 0.5 mole of sodium bisulfate and 0.5 mole of its salt and then try if the pH changes less than 10% once i add the hcl?

[Borek]

Assume the initial concentration is x and express the condition (not more than 10% change) using algebra and Henderson-Hasselbalch equation.

Then just solve for x.

[sharbeldam]

Thank you borek
we appreciate you and this site.