A buffer is prepared by mixing #1*mol# of acetic acid with #1*mol# of sodium acetate...what is the concentration of the buffer?

1 Answer
Nov 12, 2015

Answer:

The molarity is #1.0# #mol*L^(-1)# with respect to both acetic acid, and to sodium acetate. On the other hand, if you have mixed equal volumes of acetic acid and sodium acetate, then the concentration is #0.5# #mol^(-1)#

Explanation:

As you know, this is a buffer solution, whose #pH# would remain very close to the #pK_a# of acetic acid (which is from memory #4.76#).

#pH = pK_a + log_(10){[[OAc^-]]/[[HOAc]]}#.

#HOAc# #=# #H_3C-C(=O)OH#

As I said before, if you have taken equal volumes of #1.0# #mol*L^(-1)# acetic acid and sodium acetate, because you ADDED these volumes, (i.e doubled the volume), the concentration of each reagent is HALVED.