Finding Oxidation Numbers,Dalton's Laws Etc

[00:00:00]First of all, start with finding the oxidation numbers.

[00:00:20]How to find the oxidation number?

[00:00:38]Sorry. Um, don't know. I just got a cough just right now.

[00:00:51]Okay. So sometimes it could be in your MCQs or just in your section as answer in your one word answer they might ask you a question where they would ask you to find the oxidation number of a particular element in a compound. Okay, they might ask you such a question. For example, they might say find the oxidation number of let's say chromium.

[00:01:36]Okay, let's say chromium in this particular compound.

[00:01:49]Does anyone have an idea how to solve such a question?

[00:01:55]Anyone with an idea on how to solve such a question?

[00:02:17]Okay. So, seems no one has a has has has an idea. So, let me give you now the idea.

[00:02:25]Find the oxidation number of chromium in this.

[00:02:30]This looks like uh chromium peranganate.

[00:02:34]It's a peranate ion actually. So, If a question comes, okay, if a question comes in chemistry, they ask you to find the oxidation number.

[00:02:54]The first thing you're going to do, ask yourself, oxidation, what does it mean? It implies that there's a link between the one element and oxygen. Okay? you attaching oxygen atoms or molecules to a particular element.

[00:03:14]So now this chromium has got two atoms.

[00:03:23]Two atoms.

[00:03:26]Oxygen has got how many atoms?

[00:03:30]Seven atoms.

[00:03:33]Seven atoms.

[00:03:35]But this particular oxygen or this particular oxygen that we're talking about has got a charge.

[00:03:46]Okay?

[00:03:48]And the charge is -2.

[00:03:59]It's a -2 because I've got a -2 this side a negative recharge. So for you to find the oxidation number of this guy ask yourself how many atoms of chromium do you have?

[00:04:16]Hello. Can someone just answer me? How many atoms?

[00:04:22]>> Two.

[00:04:23]>> Two. So you're going to say 2 X. How about if there was one chromium would have said X.

[00:04:35]But for this one you say 2X.

[00:04:40]Then you're going to add plus.

[00:04:44]Okay. You say plus.

[00:04:47]Then you ask yourself this one question.

[00:04:52]What is the charge of oxygen? What is the what what how many number of atoms of oxygen do you have?

[00:05:05]The number of oxygen atoms you have seven.

[00:05:10]So this seven inside here you are going to you're going to put the charge of oxygen. So you say -2 then at the far end there you still you still put the charge of oxygen and say -2.

[00:05:39]Okay. So the first thing we did we asked ourselves how many atoms of chromium we said there are two. So I said 2x. Then how many plus how many atoms of oxygen do we have? Seven. Then this seven multiplied by the charge of the number of oxygen atoms that you have then equal to the charge given which is 2 negative.

[00:06:06]So if you continue are going to find your 2x then 7 * -2 is going to give us -14 = -2. So this will be 2x = -2 + 14.

[00:06:25]2x is going to = 12 over -2 over -2. So your x is going to equal to + 6. Okay, + 6. So the oxidation number of chromium in this particular compound is + 6.

[00:06:53]+ 6.

[00:07:08]Okay.

[00:07:10]Any question?

[00:07:22]Let me do another one. I show you the simplest of the simplest way. Okay. The second one we are going to do is this guy here.

[00:07:36]We find the oxidation number.

[00:07:43]This is a peranganate.

[00:07:45]We find the oxidation number of manganesees.

[00:07:49]We find the oxidation number of manganesees.

[00:07:54]So let's ask ourselves how many atoms of manganesees do we have?

[00:08:05]>> One.

[00:08:06]>> So what are we going to say?

[00:08:12]Are we going to say two eggs or eggs?

[00:08:18]>> X.

[00:08:19]>> Okay. So let me put them together first.

[00:08:22]So, how many atoms of manganese?

[00:08:26]One atom. Okay. How many atoms of oxygen?

[00:08:31]Four atoms. What is the charge of oxygen?

[00:08:40]-1.

[00:08:42]So, the one who who was talking to me, you you can unmute yourself so that we talk again. Huh? What what what were you saying? What are you going to put? X or one?

[00:08:56]>> We're going to put X.

[00:08:58]>> Very good. Plus Yes. Then what are we going to do next?

[00:09:04]>> + 4.

[00:09:06]>> Very good. 4 >> 4 *1 >> -1. Very good. What is it going to equal to?

[00:09:20]equal to1.

[00:09:21]>> Very good. Any any question? Any person who is having who who has been left out here?

[00:09:28]Anyone who has been left out here.

[00:09:39]Okay, so this is someone wanted to talk.

[00:09:46]So this will just be the same as x - 4 = -1.

[00:09:55]x is going to = -3 + 4. x is going to = + 3. So oxidation number of manganesees in this uh particular uh uh compound is + three.

[00:10:18]Okay.

[00:10:20]Let's try this one.

[00:10:29]Let's try this one.

[00:10:32]We have a sulfate ion.

[00:10:37]I want the guy to do it. I want the guy to do it. Yes.

[00:10:45]What is the first thing we are going to pick? Let's pick. We want to find the oxidation number of sulfur. Mhm.

[00:10:57]How many atoms of sulfur do we have?

[00:11:07]Hello. How many atoms of sulfur do we have?

[00:11:14]>> One.

[00:11:15]>> One atom. No, don't mute yourself. It's okay. Let it be interactive. I like it like that. So s has got good life. How many atoms of sulfur do we have?

[00:11:35]One.

[00:11:36]>> One. Don't mute yourself. Good life. I want you to speak to me then. How many atoms of oxygen do we have?

[00:11:57]>> Four. What is the charge of oxygen?

[00:12:07]>> -2. So now how how are you going to make your equation? Yes. You you tell me how I going to make the equation. Yes.

[00:12:23]>> Yes.

[00:12:26]X.

[00:12:28]>> Yes. Please put in confidence. X Yes.

[00:12:35]>> 2 * -2 >> = -2 >> is = -2.

[00:12:50]Right?

[00:12:54]So this is going to be x mhm - 8 is = -2.

[00:13:04]So x is going to equal to -2 + 8 and then you're going to get + 6.

[00:13:14]Have you seen how we are getting the oxidation number?

[00:13:21]like this.

[00:13:23]>> It's that simple actually.

[00:13:26]>> Okay.

[00:13:37]>> It's that simple. I want you to try out this one.

[00:13:47]I want you to try out this one.

[00:13:52]Oxidation number of >> Okay. So, let me just give you let's say four. I'm going to say >> Okay, you try that one.

[00:14:12]Try out that one. Let's see.

[00:14:29]What are you getting?

[00:14:33]What are you getting?

[00:14:49]You're getting two.

[00:14:53]>> You're getting a two. Okay, let's let's check it out.

[00:14:58]Let's check it out.

[00:15:01]How many atoms of sulfur do we have?

[00:15:06]One.

[00:15:08]Oxygen how many do we have? Three.

[00:15:12]Charge of oxygen it is -1. So this is going to be x + 3 the -1 =1.

[00:15:27]So this is going to be - 3 =1.

[00:15:32]So x = -1 + 3. So x = + 2. Very good. This is the oxidation number for sulfa in for for that for sulfur in that particular compound guys.

[00:16:01]No, >> but they but you you didn't know how to solve them, right?

[00:16:11]>> Yes.

[00:16:14]>> Okay, let's try out another one.

[00:16:18]The other one which I want us to solve maybe I bring the this one let's find the oxidation how about if it is presented like this what is the oxidation number I want you to try out for carbon dioxide let's What are you getting for carbon dioxide?

[00:17:31]Hello, you guys. What are you getting?

[00:17:48]>> I think zero.

[00:17:50]>> Someone is saying >> yeah, even me I've gotten zero.

[00:17:55]>> Okay. So, how many atoms of carbon do we have?

[00:18:02]One.

[00:18:04]How many oxygen atoms do we have?

[00:18:08]Two.

[00:18:10]What is the charge of oxygen in this case?

[00:18:21]zero. But this guy here is neutral. This guy is not charged.

[00:18:31]So for for for something that is not charged or for for a molecule or for a compound that is not charged acknowledge that oxygen has got a net charge of -2.

[00:18:45]Okay.

[00:18:47]So acknowledge that oxygen is going to have a net charge of -2. So your equation is going to be like this. Since you have a carbon of of of one atom, it will be X there. The same way plus then how many atoms of oxygen?

[00:19:05]Two. Now the question is what are you going to put here? You won't put a zero.

[00:19:14]You put the charge of oxygen.

[00:19:17]What is the charge of oxygen?

[00:19:24]If it's >> If it's not given, >> if it's not given, it's -2. Put that in your head always. If it's not given, it's -2.

[00:19:42]Then this is going to be equal to then you put the charge here zero at the end.

[00:19:54]So this is going to be x plus this is going to be -4.

[00:20:05]So this is going to be equal to 4 + and that becomes the answer for carbon dioxide.

[00:20:24]Clear.

[00:20:29]How about for this guy here?

[00:20:32]How about for this guy for this guy? Find the oxidation number there.

[00:21:03]>> What are you getting?

[00:21:13]Uh I'm getting um positive2 >> positive2. So let's check how many atoms of carbon one atoms of oxygen one charge of oxygen zero.

[00:21:35]But we know that oxygen is going to have it's going to have a particular charge somewhere because it's neutral. So this just the same as x plus then this going to be a one open bracket -2 equal to z.

[00:22:06]Okay we have taugh that is how you solve it when you're dealing with oxygen. Any question?

[00:22:17]I want you to try this one as a task.

[00:22:25]As a task, let me give you this one.

[00:22:28]Okay.

[00:22:30]Find the oxidation number of this sulfur in sulfur dioxide.

[00:22:38]Just 2 minutes.

[00:22:41]2 minutes. 2 minutes. 2 minutes.

[00:22:47]What are you getting?

[00:23:01]>> What are you getting?

[00:23:05]Uh 44.

[00:23:08]Yeah.

[00:23:13]I've gotten a pos4 the other one. What are you getting?

[00:23:23]Good life. Chimoka, what are you getting?

[00:23:35]Okay. So we have one sulfa atom, two oxygen.

[00:23:42]The charge of oxygen sorry the the charge of the of of oxygen for this particular compound is zero.

[00:23:54]But we know that oxygen is going to have a net charge of -2. So this is going to be x + atoms we have two -2. then this is going to be zero.

[00:24:07]So this is going to be x + -4 = 0.

[00:24:21]So of course x is going to equal to plus [Music] sarah your mic is on sarah your microphone is who who found uh someone found plus plus 4 okay it's it's okay that is the correct answer now how does it change how does how does finding ox oxidation number change if you if you if you are dealing with hydrogen.

[00:25:02]For hydrogen, remember that hydrogen has got a positive partial charge like this.

[00:25:15]So instead of having -2 we shall be having -1 sorry + one in hydrogen. So whenever you see they want you to find the oxidation number and there is hydrogen in there don't even waste time. You will be adding one.

[00:25:42]Okay, depending with the number of atoms given a very good example, we are going to have an an atom which is going to sorry a compound which is going to be neutral.

[00:25:58]So I want to find the oxidation number for sulfur in this particular compound.

[00:26:03]the same concept. Let's ask ourselves how many atoms of of hydrogen do we have?

[00:26:15]Sarah atoms of hydrogen there are two.

[00:26:31]What is the Number of atoms of sulfur it's also it's just one.

[00:26:40]What is the charge for this whole thing is neutral so it's zero.

[00:26:50]So since it is zero here we know that t what is the net charge of hydrogen?

[00:27:00]It's going to be Sorry, positive one. That's the net charge of hydrogen. Positive one.

[00:27:10]It's here. You can't just see it. So you say X plus then the same thing. Okay, we add two atoms multiplied by post + one equal to zero. So this is just the same ones. X multiplied by this guy is going to be + 2 = 0. So this one is going to have a net oxidation number of -2. Simple. That's how you find.

[00:27:56]Hello Any question?

[00:28:25]Any questions? Sarah, you just recently joined Sarah.

[00:28:44]I'm saying any question.

[00:29:03]Okay. No question. So I'm sure you you you you you understand how we were solving these uh these questions. I think this part is is now very simple now. I think most of you are now able to to solve this these these questions. Uh good life. Are you able to solve my oxidation number after having like this?

[00:29:28]>> Yes.

[00:29:29]>> Okay. Let's do task.

[00:29:35]Find the oxidation number of calcium in this particular compound.

[00:29:47]What is the oxidation number of calcium there?

[00:29:53]You also do for this guy here.

[00:30:09]What are you getting?

[00:30:42]What have you found for for for the first question?

[00:30:48]>> The first question is -2.

[00:30:53]>> Okay. -2. How about others? What have you found?

[00:30:58]>> The first one is that two >> and then the second one >> So let's find the first one first.

[00:31:12]So calcium one, hydrogen 2, charge zero. But we know that hydrogen is going to have charge of of positive one. This is going to be x + yes 2 * + 1 = z.

[00:31:39]So -2. Okay. Correct.

[00:31:44]Then for this one uh n sorry sodium one hydrogen 1 charge 0.

[00:32:00]So this is going to be x + 1 * + 1 = 0. So x is going to equal to1.

[00:32:11]Correct? You've understood the concept.

[00:32:13]Now let's try to do just one one one more. How about if how about if for example a compound is containing both hydrogen and oxygen. How do you treat it?

[00:32:33]Let's say they ask you to find the oxidation number in siric acid.

[00:32:45]How do we go about it? The same concept.

[00:32:51]We try the same concept. Let's check how many hydrogen's do we have.

[00:33:03]Two.

[00:33:05]S. How many do we have?

[00:33:11]One oxygen. How many do we have?

[00:33:17]Four.

[00:33:19]What is the charge for this particular compound? All of it.

[00:33:28]Zero. But we know that there's a plus one here. Don't forget there's a -2 here. So, what you're going to do is the same concept. Since you have one uh uh sulf sulfa atom, you will put your x there. Okay, you put your x then you say plus. So here you've got four oxygen atoms. So it will be four oxygen atoms.

[00:33:53]What are we going to put inside there?

[00:34:03]What are we going to put inside?

[00:34:07]-2 >> -2 plus then we do the part for hydrogen.

[00:34:15]So we have two atoms. Then what do we put inside there?

[00:34:22]>> Positive2 >> positive one positive one.

[00:34:32]Then this is going to equal what?

[00:34:41]Hello. This is going to equal what?

[00:34:45]Zero. Then you do your calculations.

[00:34:55]So this is going to be -6 = 0 and your x becomes your plus 6.

[00:35:03]Any question there.

[00:35:19]So basically that is what I that that is what I want.

[00:35:26]Okay.

[00:35:29]That is what I want. when when when they ask you a question when they ask you a question in the in the exam don't don't make a mistake because this is it's very simple actually this is how you do it all of them just use the same concept that the men has taught you you'll be able to find almost any question I want you to try out this one uh find the oxidation number of phosphorus find the oxidation number of phosphorus in this compound the finding the oxidation number of phosphorus in this compound I'm just giving you about 2 minutes oxidation number of phosphorus what I getting let's be quick actually 10 seconds. 8 seconds.

[00:36:32]8 seconds.

[00:36:42]What have you gotten?

[00:36:50]>> Okay. So we solve >> uh we are getting positive five.

[00:36:54]>> Let's Okay, let's let's check it out.

[00:36:58]>> Okay. Okay. So everyone is saying positive five. Let's check hydrogen. How many do we have? Three.

[00:37:06]Phosphorus one. Oxygen four. Charge of the whole thing zero. So but we know that there's a plus one here.

[00:37:19]There's a minus2 here. So, of course, we do the same thing. X plus it's going to be 4 the -2 plus this is going to be 3 + 1 = 0.

[00:37:38]So, this is going to be - 8 + 3 = 0.

[00:37:44]And then here we're going to get a minus 5 = 0 and our x is equal to + 5. Don't forget to put the plus the minus those are charges. At least you're able to show the examiner something. Okay. I'm sure we've now understood this part.

[00:38:00]Sarah clear.

[00:38:13]Okay.

[00:38:16]All right. So that is how we do that part. That that is how we solve such type of questions.

[00:38:23]We go back to our topic.

[00:38:30]There's a question which I wanted us to do. Okay.

[00:38:39]We go back to the things that we're doing.

[00:38:42]So this question was saying 823.8 8 L balloon is filled with 88 g of carbon dioxide at 15°C.

[00:39:31]What is what is the pressure in kilopascals?

[00:39:47]So we have a 23.8 L balloon which is filled with 88 g of carbon dioxide at 15°. What is the pressure in kilopascals?

[00:40:00]We want to find the pressure in kilopascals in the data.

[00:40:11]We have been given the mass of carbon dioxide and they are saying it is 88 g.

[00:40:23]We just want to collect the data.

[00:40:27]And then we have been told that the temperature is at 15°.

[00:40:34]We have been also given the volume one to be 23.8 L.

[00:40:45]Okay. So given looking at what we have been given here, they want us to calcate the pressure in kilopascals.

[00:40:52]Which formula we going to use? Looking at what you have been given.

[00:41:04]So looking at what you have been given, the best formula you're going to use from what we learned last time is the formula for the ideal gas.

[00:41:14]The formula for the ideal gas. I want you to give me that formula, guys. Can someone give me the formula for the ideal gas?

[00:41:32]Play show one.

[00:41:35]>> Uh-huh.

[00:41:37]>> Times volume one.

[00:41:41]>> Uh-huh.

[00:41:43]by temperature one >> ideal gas if you say divide by temperature one what are you going to do with this with this mass hello what are you going to do with the mass So this formula is not holding I want the formula for the ideal gas anyone who is having the formula for the ideal gas >> it's it's pressure time volume is equal Number of moles.

[00:42:40]>> Very good. Pressure times the volume is equal to the number of moles. Yes.

[00:42:48]>> And R.

[00:42:50]>> Very good. Have you seen that whatever you having is going to fit. So whenever you are dealing with this topic I was telling you say this topic is simple. If you collect the data and you know the formulas, what they want you to calculate is just the pressure. So you can even say over V over V. So you can cancel out. You remain with your P = to number of moles RT over V. Then you can ask yourself what is the number of moles of carbon dioxide? We can calculate them. We know that number of moles is equal to the mass over the mister. That's what we learned in our previous sessions. Carbon dioxide is 1* what is the relative atomic mass? 12. So this becomes 12. Then oxygen is a 2 * 16 and that becomes 32. All together we getting 44.

[00:43:53]Okay. 44.

[00:43:57]So you can say that number of moles is equal to number of moles of carbon dioxide is equal to what is the mass given? It is 88 over 44.

[00:44:13]Number of moles is going to equal to what?

[00:44:17]Two.

[00:44:21]Have you seen Then you say pressure is going to equal to.

[00:44:33]So since we are using um liters, which constant are we going to use? We using liters.

[00:44:46]>> We are going to use 0.0821.

[00:44:51]>> Is it the one? Is it the one which is having liters or just liters?

[00:44:56]>> It's the one which is having liters.

[00:45:00]>> It is the one which is having liters.

[00:45:02]So >> yes, >> give me what is it? 0 >> 0.0821 >> 0.0821 Then what is the temperature? I want you to help me convert that temperature in Kelvin. What are you getting?

[00:45:30]>> It's giving 288.

[00:45:33]>> 288 then divide by the volume.

[00:45:48]Let's calculate.

[00:45:51]So two uh this is going to be 2 * 08 21 then 288 uh divide by 23 08 23 23.8 8 and I'm getting >> 1 98 Okay 1.8 8 1.98 1.98 Now I want I want to ask you a question the one was written what was the pressure what was the the pressure what was the what was the pressure units in in this one for 0.028 0.0821 08 H21. What was the units of the pressure there?

[00:47:12]What was the units? Were they pass or they were ATM or they were what?

[00:47:20]>> Oh, they were ATM atm. Right.

[00:47:27]>> They were atmospheres.

[00:47:30]Okay. They were atmospheres. So now you need to use a conversion. What you have found here, this pressure found here is in is going to be in atmospheres.

[00:47:39]Have you seen how tricky this thing is?

[00:47:42]This you're going to find here is going to be in atmospheres.

[00:47:47]Why? Because you used that you used the one which you you used had its pressure in atmospheres.

[00:47:56]So you use now a conversion factor.

[00:48:00]Okay. Use a conversion factor where you say one atmosphere is going to equal to 1 0 1 325 pascos.

[00:48:21]Okay.

[00:48:22]101 325 pascos.

[00:48:26]Then 1.98 atm is going to equal to x. Let's multiply.

[00:48:34]What are we getting?

[00:48:36]If you multiply by that number 1013 32 5 I'm getting something like 101 35.

[00:48:53]Then since it's kilo pascal, you divide this by 1,000.

[00:48:59]This was in pascals. Now kilo pascal, you divide by 1,000.

[00:49:07]And our final answer becomes 101 325 kilo pascals.

[00:49:20]Any question on that?

[00:49:34]Hello.

[00:49:37]That is how you calculate for that particular question.

[00:49:42]Okay, you can conversion units converion factors are coming. There's one question which I was interested in on Dton Dton's law.

[00:49:57]>> This question was saying >> first >> hello first repeat the calculation. How come you are getting the same figures when you multiply 101 325 * 1 98?

[00:50:16]What? What are you getting there?

[00:50:28]>> What are you getting there?

[00:50:33]>> I'm getting 2,00 2,000 2,623.5.

[00:50:43]>> Okay.

[00:50:47]At least you understand the concept what I'm doing. That is what is the most important thing. So this is a 12,000. Thank you so much for the correction. This is a 2,00 206 23.5.

[00:51:08]Then we divide this by 1,000. These are pascals.

[00:51:20]and we get a 200.6 kilo pascals.

[00:51:29]All right. Thank you. So that is just how you do it.

[00:51:39]>> This question was saying a mixture of 2.0 uh a mixture of 2.0 moles.

[00:51:57]We have a mixture of 2.0 moles of hydrogen.

[00:52:07]And then we are also going to have three moles of ammonia.

[00:52:19]Four moles of carbon dioxide and 5.0 zero moles of nitrogen.

[00:52:43]They're saying it exerts a total exerts a total pressure of 800 to Question.

[00:53:12]Calculate the individual partial pressure.

[00:53:29]We find the individual partial pressure of hydrogen, ammonia and carbon dioxide as well as nitrogen.

[00:53:43]Then we then the second question is saying we find the total partial pressure.

[00:53:56]Total partial pressure.

[00:54:02]We find the total partial pressure.

[00:54:11]Okay. So we do the solution. I think I I already started open where we left on Dton's law.

[00:54:30]So remember I said when when you want if you want to uh make dou very simple just the concept is if you want to find the part okay let's do the first partial pressure we want to find the partial pressure.

[00:54:55]The partial pressure for hydrogen.

[00:55:00]The partial pressure for hydrogen is going to be the number of moles of hydrogen over the total number of moles multiplied by the total the total pressure exited.

[00:55:35]That's all. That's what I implied in the in the previous video. So, let's first of all get the to the total number of moles. So, total number of moles. Let's add everything.

[00:55:49]We have a 2 + a three plus a four. What are you getting if you add everything together?

[00:55:58]2 + 3 + a4 plus a 5 we are getting 14 14.0 moles.

[00:56:19]Okay. Then this for for us to find the partial pressure for hydrogen you get the number of moles of hydrogen.

[00:56:31]You divide them by the total which is 14. Then you multiply by the total pressure the pressure the total pressure exerted which is 800 to whatever you get that becomes the individual pressure of uh of of hydrogen. Okay. So I want I want each one of you to pick one one can find for let me give you Okay.

[00:57:06]So, uh gift I want you to find for ammonia.

[00:57:11]Then I want you to find for carbon dioxide. Quickly quickly quickly we just work out this together. We finish.

[00:57:25]So 2 / 14 * 800 we are going to get 114.28 2 H2O to okay so the one is finding for ammonia tell us the one we finding for carbon dioxide tell us let me also find for nitrogen again partial pressure of nitrogen number of moles Close.

[00:58:19]This is going to be two 85.7.

[00:58:25]What have you found for For money it's given 171.4 >> 171.4 and then for carbon dioxide what are you finding?

[00:58:49]Um before I do not get where the the TN where you get your TN from. TN is the total number of mo.

[00:59:07][Music] >> Hello.

[00:59:14]All right. So, what are you what are you finding?

[00:59:36]Okay. The other one you can calculate it also.

[00:59:54]for carbon dioxide 228.5.

[00:59:57]>> Okay, good.

[00:59:58]>> 228.5.

[01:00:01]>> Okay, so you have calculated individual pressures. Now you can find the total partial pressure.

[01:00:14]So total partial pressure we can just add up everything. 114.28 + uh 171.4 plus 228.5 plus 285.7.

[01:00:34]And this gives us 799.8.

[01:00:42]Okay. So I just wanted to maybe just find this question for you so that in case there's need for there's need for just for the sake of learning.

[01:01:03]Okay. I'm sure we have understood what what what what we wanted to learn today oxidation numbers and practice questions on what we just for the sake of revision and and stuff. So the next time we we come to meet I'll go directly to Graham's law. If these people are going to add the topic we may do it but as now at least we are up to date. We don't have a lot of things to learn. So it means that at least we can do some revisions. Make sure you send the sheets we go through. Am I helping?

[01:01:41]>> Thanks very much. All right. Thank you so much. I'll upload the session.