Posted by Anonymous on .
Two burettes are filled with solutions: one with 0,1OM CH3COOH solution, second with 0,15M CH3COONa. How many milliliters each solution will need to make 20mL of solution, which pH=4.85

Chemistry  buffers 
DrBob222,
Use the HendersonHasselbalch equation.
I would set base = millimols base = mLB*0.15.
mmols acid = mLA(0.1M) = (20mLB)*0.1
Substitute and solve for mLB, then mLA.