Chemistry 12 | Mr. Hogr | Chapter Six | hydrolysis of salt | Lesson #47

Added: 2026-05-12

[00:00:08]Salty basket.

[00:00:26]Last time I told you try to memorize list of the acids and bases with their strength al of course I mean strong acids what are the strong ba bases weak acids and the weak bases also okay and then the conjugates we need them so the title is salt hydraysis so how do we know first of all you know what is the main problem for the students In vizari in this section we have three topics. The first one salt hydraysis.

[00:01:00]The second one common ion. The third one buffer solution.

[00:01:21]In salt hydrarolysis we only dissolve one salt.

[00:01:27]We will dissolve one salt in water in water. Somebody said okay salt in water. This is called salt hydraulysis.

[00:01:38]Basha tama. Ah. So I'm going to give you a quick revise for the things that we studied together last time. Look as I said salt is an ionic compound contains of ionic assembly of a cation and anion.

[00:01:57]The cation which is called a conjugate acid and the annion is the conjugate base. conjugate base. Good. Conjugate acid can be strong and can be weak. The same thing is true for the conjugate base. It can be strong and can be weak.

[00:02:18]Okay, only the strong conjugates are going to be hydrayed.

[00:02:26]Only strong only a strong conjugate under goes the hydraysis process. What do you mean by the hydraysis by by the way or hydraysis? No problem. H what mean by the salt hydrarolysis? It means ions plus H2O with the reversible arrow. What kind of ion only strong conjugates?

[00:02:49]Okay, strong conjugate acid or conjugate base that are came from weak acids and weak bases. Okay, only these ions undergo the hydraysis process. Done. So now we have two types of hydraysis.

[00:03:10]example.

[00:03:14]So it's time for this. Look, I will solve this question.

[00:03:23]Which of the following reactions occurs?

[00:03:25]It means we we have some reaction. So let's find out if the reaction occurs or not between any of the following two species. Okay. Look, first of all, CN CN which is a conjugate base. Conjugate base. It means it came from an acid.

[00:03:43]Which acid provide the CN? HCN of course. What is HCN? A weak acid. So CN must be strong. Yeah, it reacts with water. It can reacted with water. Get.

[00:03:57]How about the wait for the product? Of course. I'll tell you how to write the product. Na. Na. Since it's a cation, so it's a conjugate acid. conjugate acid.

[00:04:08]It came from a base which is NaOH. NaOH it's a strong base. So Na+ will be a weak conjugate acid. So it cannot reacted with water. No reaction.

[00:04:21]Cl negative. Cl negative. It's a conjugate base. Conjug Cl negative. It came from HCL right? HCL it's a strong acid. So Cl negative will be a weak conjugate base. It cannot react with water because we only need the strong conjugates that are came from the weak electrolytes.

[00:04:43]Br also it's a weak conjugate base. It cannot react with water. Then how to write the product? Of course the directions must be reversible.

[00:04:54]Anytime if we have some ions some ion reacted with water the the the written direction must be reversible. Be careful. Ah so how to write the reaction for the anionic and cationic hydrarolysis? Look try to write the following points please. First of all a cationic hydraysis cationic cationic hydraysis and we have anionic hydraulysis also in contrast.

[00:05:28]an ionic hydraysis get look cationic hydraysis first of all it's a cation as we know it's a conjugate acid okay and we need strong or weak only a strong conjugate acid can react with water and a strong conjugate base can react with water so if it's a weak conjugate it cannot react if it's a strong conjugate which is came from a weak base It will react with water.

[00:06:00]Okay.

[00:06:02]Conjugate acid. Conjugate acid plus H2O.

[00:06:09]The direction must be reversible.

[00:06:11]Conjugate acid. It's a cation. Look at this please. Acids are proton donors or acceptors. Proton donor.

[00:06:22]Proton donor.

[00:06:24]H donor. Okay. H donor. our habits. So acid is a proton donor. It will provide or it donates a proton to water molecule. Water will become H3 plus what left? Look this is a strong conjugate acid. Strong conjugate acid.

[00:06:48]What will be the conjugate for this?

[00:06:50]Weak base plus weak base. Look, cation produces H3O.

[00:07:01]Since cation is a strong conjugate acid because it undergoes the hydraysis process. So it will produce its original species which is a weak base. So where did we get strong conjugate acid from a weak base? This is called nonionized molecule.

[00:07:20]Nonionized molecule. So look cationic hydrarolysis the things that are produced are increased. Look H3 is increased.

[00:07:35]PH is decreased. The solution is the solution is acidic.

[00:07:45]plus molecule of weak base increases.

[00:07:56]If we have a cationic hydraysis cation plus H2 it produces what? Just say Mr. Cation produces cation.

[00:08:05]Cation produces cation positive produces positive. Okay. H3O is increased and the relation between H3 and PH is inverse.

[00:08:13]As you know this pH is decreased the solution is acidic plus weak base molecule is increased also called nonionized forum nonioniz it forum is increased good how about the anionic okay first of all anion is a conjugate base as I said it can be weak conjugate base and strong conjugate base which one reacts with water of course strong so now we have strong conjugate base. Be careful. Mhm. Strong conjugate base which is anion. Okay. Look plus it by H2O.

[00:08:55]The direction must be reversible. Look if cation produces cation. So that means anion produces anion or since it's a base so it must be proton acceptor.

[00:09:15]proton acceptor. It's a proton acceptor. It gains proton from water molecule. It will take a proton from water molecule.

[00:09:25]So water water molecule becomes the O plus what is the opposite species for this strong conjugate base will become a weak acid.

[00:09:36]Weak acid provides strong conjugate base. weak base provides strong conjugate acid.

[00:09:43]So annion produces annion, cation produces cation. The things that are produced are increased. O is increased.

[00:09:54]PH is also increased. The solution is the solution is a basic or alkaline.

[00:10:07]Plus look molecule of weak acid is increased or nonionized form.

[00:10:20]Cation produces H3 plus molecule of weak base. Anion produces O plus molecule of weak acid.

[00:10:32]How do we know if the question related to the hydraysis we will dissolve one salt in water? One salt in water. Okay, look. I'll repeat this again. Cation which is a conjugate acid. Cation produces what? H3O.

[00:10:54]Plus molecule of what? Weak base. Annion which a conjugate base. It produces what? It produces O plus molecule of weak acid.

[00:11:07]Tama. These are increased.

[00:11:11]These are increased. Here pH is decreased. Solution is acidic. Here pH is increased. Solution is basic.

[00:11:24]But these two must be strong.

[00:11:38]salt contains cation with ionic assembly of the an to the anion I mean okay cation is a conjugate acid if it's a strong conjugate acid strong conjugate acid then it will react with water which is called cationic hydrarolysis is cationic produces H3O. Okay, pH value is decreased. The solution will be acidic plus molecule of weak base or nonionized form of weak base or concentration of weak base. These are the same they stand for the same meaning. Okay, that's all. How about the anion conjugate base? If it's a strong conjugate base, it will react it with water which is called anionic hydraysis and then it will produce O. PH value is increased. The solution is alkaline and these are increased also.

[00:12:40]I'll get back to this. Don't worry.

[00:12:45]So, which one reacts with water? Only these. These are not with the reversible arrow will be annion produces H3 H remar anion conjugate base conjugate base bases are proton acceptor it takes a proton from what molecule so it produces O+ what is the weak acid molecule right here at CN again.

[00:13:15]Come on again for the next time. Let's read this. The difference between kanic and anic hydraysis. Look, a kion is a conjugate acid. If the base is weak, then the conjugate acid will be enough strong to donate proton into water molecule. It increases H30O, it decreases pH. The solution is acidic.

[00:13:43]Cation produces H30 decreases pH. It means H30 is increased. PH is decreased.

[00:13:52]What will be this? Okay, assume we have this reaction in the exam. So, how do we know if this is a base or or acid?

[00:14:00]Identify the pairs. Okay, this is a pair. Look, uh it has one proton more.

[00:14:05]So, this is acid. This is base. Okay, the direction is uh reversible. So we know this is a a salt hydraysis. Okay, salt hydraulysis part in the book I mean. Okay, so it denotes a proton that means this is a strong conjugate acid and this is a weak base.

[00:14:30]The same thing is true for this. I've explained this to you many times. And look at this yellow. We have two acids HA acid with HB acid. Assume HA has Ka value of 1 * 10 ^ -5 and HB has Ka value of 1 * 10 ^ -7.

[00:14:57]Ka for this is greater. That means H A is a stronger acid.

[00:15:04]HA is stronger than the HB acid.

[00:15:13]Mhm.

[00:15:15]The HB acid. Okay. So, which one is a stronger acid? H A. So, this one produces A negative. This one produces B negative.

[00:15:27]These are conjugate bases.

[00:15:29]Conjugate bases. The conjugate bases will be opposite. Okay. So these two are proton acceptors because this is a stronger will become weaker conjugate base. This is a weaker will become stronger conjugate base. So the power of B for accepting proton is greater than this. But the power of H A for donating proton is greater than this. For the donating proton HA is stronger than this. But for accepting proton B is stronger than this.

[00:16:17]Type of salt acid and base and the conjugates.

[00:16:24]type of hydraysis or right here type of reaction and effect.

[00:16:33]Basically I have explained the whole things here but this is you know just it's something just like a quick revision again look we have four types of salts one two three and four the first one acidic salt right here conjugate acid for the acidic salt we only need the conjugate acid what is the conjugate acid cation Acidic salt. How to get an acidic salt from the reaction between strong acid and weak base. Acidic salt. It means a salt that has acidic property. It means the acidic parent it was stronger than the basic parent. So acid is strong base is weak. The parents. Okay. Look a produced in the reaction between a strong acid and weak base.

[00:17:29]So here if we have an acidic salt if we have an acidic salt we only need the conjugate acid. Look type of hydraysis cationic hydraysis the conjugate acid and cationic hydraysis you know cation produces air stereo air stereo is increased pH is decreased the solution is acidic plus molecules of weak base a basic salt also called alkaline salt acidic salt sour salt also sour salt Alkaline salt, we need the conjugate base here. How to get a basic salt?

[00:18:14]Basic salt, a salt that's produced in the reaction between a weak acid plus a strong base.

[00:18:22]Ah, so this time the base is strong. For the basic salt, we need the conjugate base, which is the anion. Okay. So, type of reaction will be anionic hydraysis.

[00:18:33]And you know for the anionic hydraulysis, O is produced. So, O is increased here. O is increased. PH is increased. The solution is basic plus molecules of weak acid. So, if you have acidic salt, acidic salt provides kionic hydrarolysis. Basic salt provides anionic hydrarolysis.

[00:18:53]Neutral salt. Neutral salt a salt that is produced in the reaction between strong acid and strong base. There will be no hydraysis. PH of the solution is unchanged.

[00:19:06]So if we if we add a neutral salt into any solution, it does not affect the value of pH because you know there will be no hydraysis for the ions of the of the neutral salt. Of course most importantly is the last one salt of weak acid and weak base. Here we have both cationic and anionic hydraysis.

[00:19:27]Stay with me I'll give you some details here.

[00:19:32]Salt of weak acid and weak base. Okay, we will have a cation and anionic.

[00:19:51]Okay.

[00:19:53]Salt of weak base. Oh my god, it's okay. Salt of weak base plus weak acid.

[00:20:10]There's no name for this. This kind of salt can be can be acidic, can be basic and it can be neutral also.

[00:20:24]Look the base provides the cation the acid provides the anion of the salt.

[00:20:38]The anion of the salt kine is a conjugate here. It will be a strong conjugate acid and this one will be a strong conjugate base.

[00:20:52]The cation produces H3O. Here is increased but here in contrast O is also increased.

[00:21:03]Mhm.

[00:21:05]So this one decides to decrease pH but this one decides to increase pH.

[00:21:14]Okay look at this. According to this the solution is the solution is acidic.

[00:21:24]According to this the solution is basic is basic.

[00:21:33]A big question mark. Now we just confused.

[00:21:38]We just confused between them. What to do? How do we know if the solution is acidic or basic? The point is acidic salt provides cationic decreases pH.

[00:21:50]Basic salt provides anionic increases pH. Neutral salt there is no hydraysis.

[00:21:55]PH is unchanged. Salt of weak plus weak we will have both cationic and anionic hydrarolysis.

[00:22:02]For the cation, H3O is increased. For the annion, O is increased. So if you have this salt, both H30O and O are increased together. The cation tries to acidify the solution. The annion tries to you know to to pro to provide try it tries to provide the the solution become alkaline. I mean okay.

[00:22:26]So now we will confuse between them. We don't know if the solution is acidic or basic. In this case we will say pH depends on pH depends on K a and KB value. Look for the cation we have Ka for the anion we have KB. Be careful please. Look the equilibrium constant for the cation is Ka. The equilibrium constant for the anion is KB. Okay. So in this case pH depends on Ka and KB. If look we will have both kionic and anic hydraulysis air studio and O are increased together. Therefore the value of pH depends on KB and KA. If K axam KB if they are equal valency both cation and anion are hydrayed equally pH is seven the solution is neutral. If Ka is greater than KB, Ka it means acid, it means cation. So there will be more cationic hydrarolysis. H3O will be greater than O. The solution is acidic.

[00:23:43]If KB is greater than Ka, pH is greater than 7. KB it stands for the base conjugate base of course which is annion. Okay. So there will be more anionic hydraysis.

[00:23:57]The solution will be basic. That's all.

[00:24:00]Okay. Try to compare kanic and anionic hydraulysis. We know this.

[00:24:16]Okay.

[00:24:19]Look what type of reaction occurs. Type of reaction it means type of hydrarolysis occurs in aqueous solution of strong acid and weak base salt. So we have a salt in H2O.

[00:24:33]This is a salt hydraysis.

[00:24:35]Just identify the type of salt. That's all. Just identify type of the salt.

[00:24:41]Everything will be solvent. Strong acid plus weak base. This is acidic salt.

[00:24:47]For the acidic salt, we have cationic hydraysis.

[00:24:53]A is correct. What type of reaction occurs between or in a solution of weak acid and strong base salt? Again, this is salt in H2O. Salt hydraysis. Just identify type of the salt. Weak acid plus strong base. This is a basic salt.

[00:25:13]Basic salt provides anionic hydraysis. B is correct. Just identify type of the salt. That's all. Okay. Dissolving an amount of NaCCl in water. Look, one salt in water. Again, this is salt hydrarolysis. Mhm. Salt in H2O. This is salt hydrarolysis. Just identify type of the salt. This salt is neutral.

[00:25:39]So for the neutral salt, pH is unchanged. There is no anionic and cationic hydrarolysis. PH not change it.

[00:25:48]Dissolving an amount of NaCCN in water.

[00:25:51]Again, salt in water.

[00:25:55]Okay, it means salt hydraulysis. Just identify type of the salt. NaCCN. It's a basic salt. I'm not going to explain why it's a basic salt, but basic salt an ionic increases pH. PH is increased. A is correct.

[00:26:15]Dissolving dissolving an amount of NH4 in water. Again, salt in water. NH4 Br.

[00:26:22]It's an acidic salt. Acidic salt decreases. It drops pH. pH is decreased.

[00:26:29]Which of the following has alkaline aqueous solution? Alkaline solution. It means pH is greater than seven which is a basic salt. Okay. Basic salt. Okay.

[00:26:43]Identify type of each of the following salts. This is a basic salt.

[00:26:50]This one is acidic.

[00:26:54]This is neutral.

[00:26:57]And this one is neutral also.

[00:27:22]If we have a salt, any salt, okay? Can be any salt.

[00:27:27]Look, it has a cation and anion. Look, if I say anion of the salt, what is the annion of the salt? First of all, annion is a conjugate base.

[00:27:40]Okay, look conjugate base. It came from the acid. Ah, look at this. This is the annion. Okay, assume we have F negative or we have a CL negative or we have CL negative whatever. Okay, look if it's F.

[00:27:56]F it came from HF. Where is HF? HF is a weak acid. So this one will be a strong conjugate base. Assume this is Cl. The anion is CL. Cl it's came from HCl HCl it's a strong acid so this one will be weak conjugate base or cation yellow what is the cation again take the cation and identify the strengths you'll get the answer exactly look I'll explain this anion of okay what is the anion which is a negative particle it's a conjugate base it's came from the acid which one is the acid Here we have weak acid. Okay. So what will be the annion? Weak acid. The conjugate will be strong conjugate base.

[00:28:46]Okay. Look. So this one is a strong conjugate base. Conjugate acid. No.

[00:28:52]Anion is not a conjugate acid. It's a conjugate base. This is wrong. Conjugate base. This is correct. Hydrononeium. No.

[00:29:00]Hydroxide. This is also will be correct.

[00:29:03]But just wait. Let's let's take the second part of the question. The acid is weak. Okay. So, conjugate base of a weak acid. This is the correct answer. Very easily just like this.

[00:29:19]Another question. Another question. The same question but this time we'll take the cation. Okay. Cation. It's a conjugate acid. Okay. Conjugate acid. It came from the base. The base right here is weak. So this one will be a strong conjugate acid. So which of the following is correct? Conjugate acid it's correct. Conjugate base it's incorrect. Hydroxide no. Hydrronium also wait. Just wait. Okay. Conjugate acid of a weak base. Conjugate acid of a weak base. This is the correct answer for the cat. Ya. Let's take these questions.

[00:30:01]Let's solve them. Alkaline solution can be produced from anionic hydraysis.

[00:30:07]Okay. What type of salt provides anionic hydrarolysis? Basic salt.

[00:30:14]Uhhuh. Basic salt the strong base plus the weak acid. Okay. Look. Weak acid is correct. Strong acid. No. Strong acid. No. Weak acid is correct. Then Okay. The base must be strong. Weak base. No. Strong base. Yes, this is the correct answer. Acidic solution can produce can be produced from the cationic hydraysis. So cationic hydraulysis it came from the acidic salt.

[00:30:46]Acidic salt the salt that is came from the reaction between strong acid was weak base. Okay. So strong acid we don't need weak acid. We don't need weak acid. Strong acid is correct. Strong acid is correct. And the base must be weak. Weak base. Yep. This is strong base. No.

[00:31:16]Which of the following has pH value depends on Ka and KV? It means salt of salt of weak acid.

[00:31:30]Weak acid plus weak base.

[00:31:36]Correct. Correct.

[00:31:42]How to explain the salt hydrarolysis by reactions.

[00:31:48]Okay.

[00:31:57]First of all look dissolving NaCCl in water we don't need this hydraysis this is something like a proment okay look assume we have dissolved NaCCl in water so take the salt which is NAC first of all dissociate the salt okay it will produce Na and L. Okay.

[00:32:26]Cation is a conjugate acid. Anion is a conjugate base.

[00:32:33]Na came from NaOH. NaOH is strong. This is weak.

[00:32:39]HCl. It came from Cl. It came from HCl.

[00:32:43]HCl is strong. This is weak. Okay. What kind of conjugate reacts with water?

[00:32:48]Strong conjugates. But since both conjugates are weak, so they don't react with water. There will be neither cationic nor anionic hydraysis. Look there is no hydraysis because both conjugates are weak. PH is unchanged.

[00:33:04]Okay. And type of hydrarolysis no hydraysis bashab.

[00:33:11]So first step just hydra dissociate the salt. NH4 CL produces NH4.

[00:33:19]Mhm.

[00:33:21]produces NH4 plus CL negative. Cl is a conjugate base and this one it's a conjugate acid. You know it's came from NH3 which is weak.

[00:33:35]This one will be strong and this one is weak because it's came from HCl which is a strong acid. So which one reacts with water? Only the strong conjugate.

[00:33:45]We need the strong conjugate. So here the cation can reacted with water. Type of hydraysis will be cationic hydrarolysis. Okay. Take the cation and write its reaction with water. Says it's a cation NH4 plus H2O reversible arrow.

[00:34:04]It's acid. Acids produce or they donate proton to water molecule. They produce H3O plus NH3 a weak base molecule. Okay. Look type of hydrarolysis is cationic.

[00:34:21]H3O is increased. So pH is decreased the solution is acidic plus molecule of a weak base the number will be increased basic basic saltion.

[00:34:59]Let's see how how anionic hydraysis occurs in this solution and how it increases pH. Look, it provides Na and Cl negative. Sorry, Cl negative.

[00:35:15]Okay, this is a weak conjugate acid and this one a strong conjugate base. yellow which one reacts with water strong conjugate we don't need this so there will be anionic hydraysis C plus H2O to form what anion produces anion plus the molecule of HN plus O is increased pH is increased the solution is alkaline that's all Here this is salt of week plus week day for the last time they say CH3 CO negative plus by NH4 positive a conjugate base a conjugate acid okay this one it's a strong conjugate base it came from acidic acid which is a weak acid and this a strong conjugate acid. So both conjugates react with water. This one increases O. This one increases H3O.

[00:36:32]Right? So both O and H30O are increased together. In this case, pH depends on what? Ka and KB.

[00:36:42]Please try to memorize this. The name of the salt is ammonium acetate.

[00:36:49]Ammonium acetate. Ammonium acetate. This salt has equal values for both Ka and KB. PH is 7. In this case, cation and anion are hydraized equally.

[00:37:26]Let's see. Assume we have a question like this in look at the first question here. Okay.

[00:37:33]Which of the following represents which of the following reaction represents this is must be a base of course.

[00:37:46]This is a typo.

[00:37:48]Which of the following reactions represents the anionic hydraysis?

[00:37:53]Anionic hydraysis it means we need to have annion plus by H2O.

[00:37:59]This is a cation. No. Correct. Plus H2O and charge it.

[00:38:05]Annion plus H2O. There at the product we need to have O. This one produces O. this one. No. So, this is the correct answer. I'm sorry.

[00:38:19]Okay. This one produces O. This is the correct answer. But here there is no O.

[00:38:26]So now let's find out the equilibrium constant for this. An ionic has Ka or KB. KB. Okay. KB equals to product over react. And what are the two products?

[00:38:40]O and HB and the reactant is B negative will we take H2O of course not so this is H equilibrium for the anionic hydraysis okay because we have the reaction it's very simple to write this but if in vizari we have this question which of the following represents the equilibrium constant for anionic KB how do we know which one is the correct answer because we don't have any reaction okay just say mister for the anionic the denominator must be the annion alone okay and for the cationic the denominator the the denominator look at this if we have an ionic hydraysis Okay. So it has KB KB.

[00:39:44]Okay. It will have KB in this case. The denominator must be the annion alone. Okay. The annion must be alone here plus the two products as the denominator as the numerators. Okay.

[00:40:00]So if we add H2O to the denominator, we need to get the numerators.

[00:40:06]And for the cationic hydraysis okay we have Ka in this case the denominator must be the cation alone okay with the two products as the numerators. If we add H2O to the denominator we should get the numerator.

[00:40:28]Right? Look which of the following represents equilibrium constant for the anioning. It means the denominator must be the anion alone. This is correct.

[00:40:37]This is incorrect because we have something inside of the annion as the denominator. This is incorrect. This is incorrect. Assume in vizar we have some another answer like this. How to be sure if this is correct or not. This answer is if I write this in this form will be easier.

[00:41:02]Look, because this is anionic equilibrium for the anionic hydraysis, we need to have the annion as the denominator. Add H2O to this, you should get the numerator. Yeah, exactly. For the cationic look equilibrium for the cation, the denominator must be the cation alone. If you add H2O to this, we should get the numerators.

[00:41:30]Salt hydrarolysis.