You are asked to make a buffer solution with a pH of 2.0. Use the information below to identify an appropriate choice of an acid and a conjugate base to make the buffer?

You are asked to make a buffer solution with a pH of 2.0. Use the
information below to identify an appropriate
choice of an acid and a conjugate base to make the buffer. Specify both the acid
and the conjugate base you would use. (Hint: There may be more than one right
answer to this problem.)enter image source here

1 Answer
Oct 22, 2016

Answer:

There is no simple answer to this question.

Explanation:

It is tempting to say that we should use a chlorous acid buffer, because the #"p"K_"a"# of #"HClO"_2# is close to the desired pH of the buffer.

We could then use the Henderson-Hasselbalch equation to calculate the required ratio of the acid to its conjugate base.

However, the predictions of the Henderson-Hasselbalch equation can deviate significantly from the actual values when #"p"K_"a" < 3#.

We would have to do exact calculations using the simultaneous equilibria involved.

That is probably beyond the scope of this question.