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Posted by 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!! - , 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 Henderson-Hasselbalch equation to solve for the new pH.
    Post your work if you get stuck.

  • chemistry help!! - , Thursday, December 15, 2011 at 3:05pm

    who knows,but are you good at chemistry, because I need help baddly

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