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Homework Help: PH of buffer solution

  1. Mar 13, 2007 #1
    1. The problem statement, all variables and given/known data

    Calculate the final pH of the following solutions:
    a) 65.0 ml of 0.105 M HCl and 100 ml of 0.118 M sodium acetate solutions are mixed.
    b) 100 ml of a 0.109 M acetic acid and 100 ml of a 0.123 ml NaOH solution are mixed.


    2. Relevant equations

    pH = pKa = log (salt/acid)

    3. The attempt at a solution

    for part a) i found the no.of moles of salt sodium aceate

    0.118 mol/L x 0.1 L = 0.0118 mol

    then after that I don't know how to fing the concentration of acid ... and if I know I can do the rest of the part a) using stoichiometric caluclations ... please help me with it

    for part b) the same problem

    I need immediate help beause this is due in 5 hours ... please do something about it
    Thanks in advance
     
  2. jcsd
  3. Mar 13, 2007 #2
    Last edited by a moderator: May 2, 2017
  4. Mar 14, 2007 #3

    Borek

    User Avatar

    Staff: Mentor

    1. Just assume acetate is stoichiometrically protonated by the strong acid.

    2. There is an excess of base - so there is no buffer solution. Once again, assume reaction (neutralization) was stoichiometric. pH is determined by the excess base alone.
     
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