The following figure represents solutions at various stages of the titration of a weak acid, HA, with NaOH. (The Na+ ions and water molecules have been omitted for clarity.) To which of the following regions of the titration curve does each drawing correspond: (b) after addition of NaOH but before the equivalence point? [Section 17.3]

Video transcript

Hey everyone, we're told that the images below show the different stages in the titillation of a weak acid with potassium hydroxide. Select the image that shows the titillation curve after the addition of potassium hydroxide. But before the equivalence point, no potassium ions and water are not shown for clarity. 1st. Let's go ahead and assess our images. Starting with a. It looks like we have eight of our conjugate base. So this means all of our weak acid has been converted to our conjugate base after the addition of our potassium hydroxide. So this will be actually at our equivalence point. Next, looking at B, we can see that we have four of our conjugate base and four of our acid. Now some of the acid has been converted to our conjugate base but it hasn't been completely consumed. So this means this is after the addition of potassium hydroxide. But before the equivalence point, so it looks like B is going to be the answer we're looking for. But let's go ahead and finish assessing C and D. For see we can see that we have one of our conjugate base and we have four of our hydroxide ions from this. We can see that we have none of our acid left. And the only substance in the solution is the conjugate base and our hydroxide ions. So this will be after the equivalence point. Lastly looking at D we can see that we have eight of our acid present. So only our weak acid is present and our base has not been added yet. So this will be before the addition of our base. So our final answer here is going to be be now. I hope that made sense and let us know if you have any questions.