Question
The following is an alpha plot for monoprotic weak acid HAHA(1) Estimate the pH at which is there s0.50 mixture of acid and conjugate base?(2) AtpH = 7.0. most of the substance is in the form of_ 1. HA 6.4"What is the approximate fractional abundance of the conjugate base at pH = 4.02(4) Estimate the value of Ka for the acid.
The following is an alpha plot for monoprotic weak acid HA HA (1) Estimate the pH at which is there s0.50 mixture of acid and conjugate base? (2) AtpH = 7.0. most of the substance is in the form of_ 1. HA 6.4" What is the approximate fractional abundance of the conjugate base at pH = 4.02 (4) Estimate the value of Ka for the acid.


Answers
A 0.185 M solution of a weak acid (HA) has a pH of 2.95.
Calculate the acid ionization constant (Ka) for the acid.
So the pH of the solution is three point to night. So from Ph, you could calculate the proton because calculating the proton concentration, which is tend to the night there's three points too high, equals five point one three times ten to the negative. Forthe Moller. And we know that Kay is age three o plus concentration times a minus concentration divided by H. A. And we could use the approximation this case in a top this three h real plus equals a milers equals the same number. So he used five for one one three times ten to the negative fourth square divided by the A J concentration, which is point one one five more and we've got a value is two point tonight times turn to the nectar of six.
So in this instance are weak acid, has a peek a all about six. And just to remind us of the important equation, Ph is able to peek a the vlog conjugate base, but by acid. But we have a pH about five so you can click. Start putting in some values we have. Five is equal to six at log of the conjugate base invited by the acid so we can simplify this five minus six people to log to conjugate based by by the acid you have minus one is equal to log kind of good base, divided by the acid. So then solving for the ratio we take, the in bars love to minus one look at a ratio of not 0.1.
In this problem, we're told that we have a weak mono protic acid and it's tight traded with zero 100 Moller, strong beats starting my drug side. And it requires 250 ml to reach the equivalent of point After 12.5 mm of the base have been added. The Ph is 4.16. We are asked to estimate the peka Well 12.5. Is that halfway point between for the tight rations and at the halfway point at the half equivalence point, the peak A. Is equal to the ph. So the PKA will equal 4.16 easiest problem.
In this question were given three images off three week assets ejects its by and Z and we are able to count the number of unassociated acid molecules, number of hydro near my aunts and the number off uh, a minus. Oh. I mean, uh, congregate base barbecues in each as sick. After giving us this information, there are stew rang facets according to the increasing K rallies. So what we have to understand here is that the hydro knee amount concentration is directly proportional to the okay about it. Something that has a high hydro Newman concentration is going to have a high K that so by that logic, we can dio that the I said with with the least amount of height on your minds it checks is the oh biggest asset. Did the Smarr list okay, value Next is going to be each z. And finally the acid with the greatest number of high Donia. My chance is going to be the man with the They just gave value it being the strongest and be there are us do rank these assets according to the increasing PK A values for the Pekka in value. It's going to be inversely proportional to the K A values. So something that has, uh, lower PK that you belong. This, however hi o K about you. By this logic, we can tell that the trend here is going to be the exact opposite off the answer to park a so and to be edge by first. Then I just see. And finally it checks faster, greater speaking, a value corresponding to the, um weakest, as it in part C were asked to rank the conjugated basis off these assets according to their increasing PKB values you might be up to understand is that if something has, ah, a friend Okay, if I knew, it's conjugated base is going to have a lower PKV Valley because the some of these tools is a constant and if minus increasing, the other has to decrease. So according to that logic, we can tell that X minus. Being the strongest base has the smallest speak every value My minus starting line Z mice Z minus comes next and finally by minus has the largest speaking the value corresponding to the because congregate base. In the next part, there are asked to calculate the person's association off checks so the present association can be dick 10 as X minus, which is the congregate base for checks divided by the in Asia. Number off. It checks molecules multiplied by 100 so picked of the currents off thes thesis and said the So what's with those numbers? We can calculate the dissociation percentage for a checks. The number of X minus molecules that we can see in the image is to the number off it checks. Molecules that were present at the beginning is equal to eight. This six currently in the objects acid. And there were two checks molecules that were present at the beginning and now have dissociate so hard to get the It's eight and it's the magic night. This by 100 get 25%. That is the percent association for it checks in the final part of the question. Sorry, he in the final part of the question, um, now asked if they had equal molar amounts off the sodium sauce off each asset and we dissolve that thing. Orta, Which solution would have the highest bureau ridge and the lowest beach? So the highest feel rich we're correspond to the lowest ohr and concentration. So the lowest or China concentration is going to be coming from the weakest base. And we've already established the best chance according to this gender. And we know that my minus, which has the greatest PKV value, is going to be the congregate base that has, um that is the biggest base. So and by there, 30 a. M start off by minus is going to be the, uh, the side that will give rise to the greatest your its value. And if something at the greatest video it's value, it is also going to have the knowest ph value because the village, um, and the beach, if you sum them together, they're going to be a constant. So if one increases start, there has to decrease. So again, it's any lie that has the smallest be its value as well. So anyway, I has bought the largest view, its value and the smallest ph value