[Methylbenzenoic]

I want to prepare a buffer using Lactic acid ( Pka=3.85)
and I want the PH of the buffer to be 3.55.
How do I go around working the conc of my acid and its salt I need to
prepare the buffer ?

Can I use

..   WEAK acid conc = (10^-3.55)^2 / (10^-3.85)

and then calculate my salt concentration ?

thanks.

[Borek]

Henderson-Hasselbalch equation