What is the pKa of buffer solution #HC_2H_3O_2# when HCl is added?

(HCl is part A)
part B: What about when NaOH is added?

(Google didn't tell me anything lol)

1 Answer
Jul 31, 2018

Answer:

Look at the buffer equation....and we address #pH# NOT #pK_a#, the which is the acid dissociation constant....#pK_a# #HOAc=4.76#.

Explanation:

A buffer is where a weak base, and its conjugate acid are mixed together in appreciable quantities to give a solution that resists gross changes in #pH#...and for such a system...

#pH=pK_a+log_10{[[A^-]]/[[HA]]}#

In this scenario, where acetic acid is used as the acid...

#pH=4.76+log_10{[[OAc^-]]/[[HOAc]]}#

Addition of acetic acid OR acetate ion (OR #H_3O^+# or #HO^-#) should change the #pH# of the solution only marginally. What will be the #pH# of the buffer if #[""^(-)OAc]=[HOAc]#