Posted by DrFunk on Monday, July 13, 2009 at 1:10pm.
A beaker with 195 mL of an acetic acid buffer with a pH of 5.00 is sitting on a benchtop. The total molarity of acid and conjugate base in this buffer is 0.100 M. A student adds 8.20 mL of a 0.260 it M HCl solution to the beaker. How much will the pH change? The pKa of acetic acid is 4.760.

chemistry help!!  DrBob222, Monday, July 13, 2009 at 3:45pm
Call base = B (acetate ion).
Call acid = A (acetic acid).
A + B = 0.1 M
pH = pKa + log (B/A).
Two equations and two unknowns. Solve for A and B.
You know pH and pKa, so solve for B/A.
Then A + B = 0.1
That is the first part of the problem.
For the second part, recognize that
HCl + B^ ==>A + Cl^ (HB is the acid, A).
You know B and you know how much HCl is added, so redo the HendersonHasselbalch equation to solve for the new pH.
Post your work if you get stuck. 
chemistry help!!  kim, Thursday, December 15, 2011 at 3:05pm
who knows,but are you good at chemistry, because I need help baddly