How many mL of 0.05 M sodium acetate should be added to 100 mL of 0.05M acetic acid to make a buffer of pH 5.1? What is the molarity of the resulting buffer with respect to acetate (Acetate + Acetic Acid)? pKa acetic = 4.76

Explanation:

Let us assume that volume of acetic acid added is V ml.

So,  

and,  

Expression for the buffer solution is as follows.

     pH =

     5.1 =

         0.34 = log V - 2

         log V = 2.34

or,        V = 218.77 ml

Now, we will calculate the molarity of the buffer with respect to acetate as follows.

  =

  =

  = 0.0499 M

or,  = 0.05 M (approx)

Thus, we can conclude that molarity of the resulting buffer with respect to acetate is 0.05 M.

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