The following diagram represents a buffer composed of equal concentrations of a weak acid, HA, and its conjugate base, A-. The heights of the columns are proportional to the concentrations of the components of the buffer. (c) Which of the three represents a situation that cannot arise from the addition of either an acid or a base? [Section 17.2]

Video transcript

Welcome back everyone. The image below shows a buffer with equal amounts of weak acid H. A. And its consequent base A minus. If our column heights pertain to the amount of the component present, select the image which shows a scenario that does not occur because of the addition of a base or an acid. So looking at scenario one, Scenario one is suggesting that if we add an acid or base, our concentration of weak acid and conjugate base will decrease to the same amount. We want to actually disagree with scenario one because if we look at scenario two we can see that our concentration of weak acid actually decreases to this lower amount here. And so this would only occur with the addition of a strong base. If we were to add a strong base, that would make sense as to why our concentration of weak acid decreases from its initial height where it was at a higher concentration. Whereas in scenario three we can see now that we have the lower concentration or decrease in concentration of our conjugate base to this level here. And so this would occur with the addition of a strong acid. And so we can confirm that the scenario one that is given to us would not occur with the addition of an acid or a base. We have to have one of our concentrations of either our weak acid or our conjugate base. That changes based on these based on either of these editions. And so we would say that image one will never be achieved with the addition of a base or an acid. So Image one is our final answer, which corresponds to choice A in the multiple choice. I hope everything that I reviewed was clear. If you have any questions, leave them below and I will see everyone in the next practice video.