Which of the following can be classified as buffer solutions...

Which of the following can be classified as buffer solutions? $$ \begin{array}{l}{\text { a. } 0.25 M \mathrm{HBr}+0.25 \mathrm{M} \mathrm{HOBr}} \\ {\text { b. } 0.15 \mathrm{M} \mathrm{HClO}_{4}+0.20 \mathrm{M} \mathrm{RbOH}} \\ {\text { c. } 0.50 \mathrm{M} \mathrm{HOCl}+0.35 \mathrm{MKOCl}}\end{array} $$ $$ \begin{array}{l}{\text { d. } 0.70 M \mathrm{KOH}+0.70 \mathrm{M} \text { HONH_ }} \\ {\text { e. } 0.85 \mathrm{M} \mathrm{H}_{2} \mathrm{NNH}_{2}+0.60 M \mathrm{H}_{2} \mathrm{NNH}_{3} \mathrm{NO}_{3}}\end{array} $$

Labs

Want to see this concept in action?

NEW

Explore this concept interactively to see how it behaves as you change inputs.

View Labs

Transcript

00:02 This question asks us to identify some buffer solutions.

00:06 So we have to know that a buffer solution is a mixture of either a weak acid with its conjugate base or a weak base with its conjugate acid.

00:16 And so that's what we're going to be looking for in each of the choices below.

00:21 So the first choice here gives us a strong acid.

00:25 Hydrobromic acid is a strong acid.

00:27 And we can basically stop right there because, again, it has to be a strong acid.

00:32 Weak acid to be part of a buffer solution.

00:35 So this is not a buffer.

00:38 The answer is no.

00:40 And in addition to that, even if this were a weak acid, notice that the conjugate base, as it were here is actually another acid, it's hyperbromous acid.

00:53 We would need to have the bromide ion present as the conjugate base here.

00:59 So that's not even the right conjugate base.

01:01 And in fact it's another acid.

01:03 So for a couple of reasons, this is not a buffer solution.

01:07 The next answer choice uses perchloric acid.

01:12 This, again, is a strong acid.

01:15 And it's a mixture of that.

01:18 Again, it would have to be the conjugate base, the perchlorate ion that would be mixed in, even if this were a weak acid, and it's not.

01:26 It's a strong base here, rubidium hydroxide...