Question

You prepare a 1.0-liter buffer solution that is 0.07 M, in acetic acid, and 0.035 M potassium acetate. Which of the following actions will destroy the buffer?

A) All these additions

B) Adding 0.035 M potassium acetate

C) Adding 0.005 M NaOH

D) Adding 0.035 M HBr

E) No Correct Answer

Answer 1

If we add HBr to this buffer, the conc of acid will increase and conc of salt will decrease by this amount.

This is because of the following equilibrium which has been established in the buffer:

CH3COO- + H2O ---> CH3COOH + OH-

So, if HBr is added, H+ will increase which will react with OH- to form H2O. So reaction will shift towards right.

So essentially, acid conc will become: 0.07+0.035 = 0.105 M

Salt conc will become: 0.035-0.035 = 0 M approx

This will destroy the buffer.

So the correct answer is:

Adding 0.035 M HBr