LOK G LIVE | PUC-II | 6.45 AM | CHP1 SOLUTIONS

[00:00:09]Hello. Hello. Good morning.

[00:00:14]Good morning. Can I know your name?

[00:00:16]Sanju Chandu.

[00:00:20]Can I know your name?

[00:00:28]class.

[00:00:30]Sorry.

[00:01:02]Take deep breaths.

[00:01:46]Yes. Good morning my dear students. In the last class uh we'll we are studying problems on concentration of solution. I think I'm left with the fifth problem from the calculate the mality. You are asked to calculate look at the problems. How to solve problems on mality when percentage is given? We'll see today marity.

[00:02:20]marity.

[00:02:26]C mole fraction mole fraction of potassium iodide. Potassium iodide.

[00:02:41]If the density, if the density, if the density mass by mass aqueous of potassium hydroxide aqueous if the if the density sorry of 20%age mass by mass of potassium iodide is 1.292 g per mole per liter g per liter.

[00:03:30]Look at here. So g per cc g per milll is the question.

[00:03:39]See let us try to understand how to face this particular problem. You are asked to calculate mality marity ball fraction all the three of them. First of all you must know what is the formula of mal mality small m is given by see first of all you recall the formula you are going to use and the requirement from the data. Mality formula is the number of moles divided by mass of solvent in kg.

[00:04:16]Okay.

[00:04:19]Second one is marity capital m is given by number of moles of the solute. Number of moles of the solute. number of moles of the solute divided by volume of solution in liter. Remember the formula.

[00:04:44]And what else is asked? Mole fraction.

[00:04:48]Mole fraction of there are two components. Mole mole fraction of potassium iodide is given by number of moles of potassium iodide divided by mass of mass of solvent. What is the solvent here? They have said that it is aqueous solution. What do you mean by aquous solution?

[00:05:14]Mole fraction of 20% by mass by mass of aquous potassium hydroxide. They have given aquous potassium hydroxide.

[00:05:23]Whenever aquous is there, solvent is mass of water.

[00:05:28]You have to take first of all you must know the formula correctly and according to the formula you must go on collecting these informations. Then you can find it first. Then you take the given. What is the data given? First they are given is the concentration of potassium iodide.

[00:05:51]The concentration of potassium iodide we write generally in square bracket like 20%age by mass by mass. 20% is mass by mass. What is the meaning of it? That is mass of water mass of potassium iodide will be 20 g.

[00:06:12]Then mass of solvent. What is the solvent here? Water. Mass of water is 80 g. Okay.

[00:06:24]First of all, we have to calculate mality. So to get the mality, what is required to you? You must take the number of moles of the solute. Number of moles of the what is the solute here?

[00:06:37]Here solute is solute is potassium iodide.

[00:06:42]Solvent is water. Carefully study the formula and the requirement to get the marity and mole fraction of potassium iodide. Mole fraction of potassium hydide is given by pot number of moles of potassium iodide. Number of moles of potassium iodide plus number of moles of water because mole fraction is given by number of moles of the component divided by sum total number of moles of the component in the solution. These three formula should keep it in or first let us see the mality. To get mality in the numerator we want number of moles of the solute. What is the solute here?

[00:07:26]Potassium iodide. What is the formula to get the number of moles of potassium iodide? That is mass upon molecular weight out of 100 g. What is the mass? Mass mass of potassium iodide is 20 g.

[00:07:43]Okay. Molecular weight of potassium hydide. Potassium is 19. Atomic weight is 19 and that of iodine will be 127.

[00:07:56]Approximately 9 + 7 is 16 carry 1. Then 2 + 1 3 + 1 is 4. You get 146 g.

[00:08:07]Potassium pot sorry potassium atomic atomic mass of potassium atomic mass of potassium you take 39 sorry 39 or even you can take 40 also plus 127 atomic number of potassium is 19 add them 9 + 7 is 16 carry 1 3 + 3 is 6 then 166 Six is the atomic weight of it. Now you calculate Now you calculate the ratio number of moles.

[00:08:48]Yes, you can continue 166 g.

[00:08:53]What is 20 upon 166 will be? Calculate.

[00:08:59]20 upon 166. You can use simple calculator. 2 divided by 166 it will be 0.12 0 you can take 0.120 is the mole is the number of moles now is the ground ready to get mality yes the first question asked is mality you have the formula already number of moles of the solute we got it as number of moles of the solute is.120.

[00:09:35]Number of moles is 0.120 divided by what is the mass of the solvent?

[00:09:44]Mass of the solvent in kg. Now it is 80 g 80 g you can get in kg to get in kg divided by,000 then you get in kg 000 cancel 0.08 08 there. If there are two zeros, you shift the decimal point two places to the left. You got now 0.08.

[00:10:12]Now you take the ratio of it.

[00:10:15]It is 0.120 approximately.

[00:10:21]We can get 0.120 divided by 0.08.

[00:10:30]It will be mality will be 1.5 m or simply you can write m it is 1.5 molar per or mole per kg. Any doubts here?

[00:10:52]Any doubts here?

[00:10:54]Okay. Second question.

[00:10:59]Second question, marity. What is marity of the solution?

[00:11:04]That is marity is given by number of moles upon volume of the solution in liters. They are asking. Okay. Now the question is number of total number of sorry volume of the solution in liter.

[00:11:20]For that you are given with the density.

[00:11:23]What is the meaning of density?

[00:11:26]1.292 22 g of the solute is present in one liter of the solution.

[00:11:32]That is the density. So 1 cc means 1 cc of solution.

[00:11:40]One cc of solution contains how many gs?

[00:11:44]1.2 22 g density is given by density is given by mass divided by volume of solution.

[00:12:00]density is given by mass divided by volume of the solution. Now how can we get volume of the solution? Because we want volume of the solution in liters.

[00:12:12]For that you have to take what? This 1.0 1.208 g mass is already given to you. Right?

[00:12:21]Now you are given with the density.

[00:12:23]Density is given to you. Now to get the volume you take volume to the left, density to the right. Right? To get marity we want number of moles of the solute already. What is the number of moles of the solute?

[00:12:40]Number of moles of the solute is 1.120.

[00:12:42]Number of moles of the solute to get mality. Numerator is ready 0.120.

[00:12:50]But you have to get the volume of the solution in liter.

[00:12:58]Is that clear to you? Density is given then of the solution in liter. How much?

[00:13:10]What is the what is the number of moles of the solute? Number of moles of the solute is given by mass divided by molecular mass.

[00:13:24]Okay. Mass of the we can get the mass of the potassium divide the molecular weight of the potassium. you'll get the mass of the potassium added is given already that it is 20 g. Okay. What is the density to get the volume of the solution?

[00:13:45]Density is given by mass divided by volume.

[00:13:49]If you take volume to the left, you get mass upon density.

[00:13:55]So mass in g of potassium added is 20 g.

[00:14:00]Then you get volume of the solution 20 g by density is given as 1 what is the density 1.2 g per cc 1.2 20 g 1.292 22 divide it 20 upon 20 divided by 1.2 will give you 20 divid by 1.292 22 give you 16 64 you can take round it off 64 you can take this this many cc but you have to convert it in one of the solution in liter clear it to one of the solution in liter to get it you have to multiply it with 1,000 or divide cc cc C it should be converted into liter because 1 liter is equal to 1,000 cc.

[00:15:13]Therefore to convert it into liter conversion factor is 1,000 divided by 1,000 you will get 0.016 64 liter.

[00:15:28]So this particular volume will contain what volume of the solution you got 0.0 01664. You can write now substitute the values you got already. You asked to get the marity.

[00:15:45]Mality. Marity. You got marity. You get huh?

[00:15:55]Volume of the solution.

[00:16:02]Total mass of the solution you're taking mass of the total mass of the solution I'm sorry total mass of the solution divide by density because volume of the solution if you need to take the mass of the solution total mass of the solution 20 + 80 is 100 you will get I think 100 upon mass of solution because to get of the solution you have to take mass of the solution not only solute 100 upon 1 100 divided by 1.2 22 83.19 46 cc convert it into liter for that you have to divide it by 883.194 divided by 1,000 you will get now shift uh three decimal places to the left 0.083 1 9 you can take it approximately liter now you can substitute the values to get mality it's very easy so what is number of moles of the potassium matter 1.1 to0 total volume of the solution will be 0 0 83 1 9 now you divide and get the value close value 020 divided by 08 31 9 we'll get the answer as 1.442 mol approximately 1.442 442. I hope you understood the point. So to get the marity you need number of number of moles of the solute. What is the number of moles of the potassium that you we calculated is.120 mole you wrote it in the numerator. Then you have to find out volume of the solution liter given density. When density is given it is density of density is given it is mass by volume.

[00:18:29]Then volume of the solution will be equal to will be equal to that is mass of the solution divide by molecular weight sorry mass of the solution upon density of the solution.

[00:18:48]So density of the solution is given.

[00:18:50]Substitute the value of density and uh we got it as 1.292 2 not to given 83.1946 mass of the solution will be 100 g totally percentage.

[00:19:03]So mass of the solute is 20 solvent is 80 80 + 20 will be you have to take solution mass of the solution 100.2 gives you gc convert it into liter and now you can calculate number of moles upon volume of the solution in liter you'll get 1.442 442 m. Take the third part of it. Third part of it is the mole fraction. I'll run this part.

[00:19:31]I'll run this part. Let us calculate mole fraction. To get the mole fraction, you need the number of moles of both.

[00:19:38]Which one? What is the formula to calculate mole fraction? Mole fraction of K of potassium iodide is given by K of potassium iodide. Sorry. Number of moles of potassium iodide divided by number of moles of potassium iodide plus number of moles of water.

[00:20:01]What is the number of moles of potassium iodide? Number of moles of potassium iodide.

[00:20:07]Just now we calculated calculated I think it is mass of the potassium is 20. Number of pulse of potassium just now calculated mass of the iodine is 20 divide by divide by molecular weight of the potassium. Just now you got it as potassium is 39 plus 127. You are getting 20 upon it is uh 140 16 carry 1 just now you got it 9 + 7 16 carry 1 2 + 1 is 3 3 + 1 is 4 molecular weight sorry 127 + 39 9 + 7 is 16 carry 1 5 I think it It is 20 divided by molecular weight 16 car 4 + 2 6 it is 166 and just now you did it again I'm showing you 20 divided by 166 gives you 0.120 just now you got now to get number of moles of water.

[00:21:32]What is the mass of water taken here? 80 gide the molecular weight of water is 18. 18 1 18 5 are sorry 80 by 18 / 18 gives you 444.44 444. Now you can calculate mole fraction of potassium mate easily.

[00:22:01]Taking the number of moles of potassium is 0.120 divide by take number of moles of potassium is.120 plus 4.444.

[00:22:13]You can get the close answer.120 by 4 + 0 is 4. 4 + 2 is 6. 4 + 1 is 5.

[00:22:22]you get 4 564 right point you can divide it 0.120 divided by 4 564 answer will be 026 29 mole that is the mole fraction mole fraction mole fraction will have no units as the number of moles number of moles cancels you'll get 0.02629 026 29.

[00:23:00]So that's all the problem my dear students. I hope you got it. First you write the formula then you prepare the requirement to calculate number of moles of the solute. So like this one by one you details you calculate percentage means in that 20 g will be potassium remaining 80 g will be water.

[00:23:20]Right? So that is the solution of this problem. We'll see some end text questions.

[00:23:28]they are not very easy. Therefore, I'm taking one extra session for calculation. Many students neglect this area directly. If you go to solve the competitive exam questions, you'll not have the in-depth understanding of the problem. See in the exercise NCERT problem number 1.4. If you have test book, you can open it. The problem is concentrated nitric acid concentrated HNO3 nitric acid used in the laboratory used in the laboratory used in the laboratory in the lab.

[00:24:14]in the lab work is 68% nitric acid.

[00:24:23]This is called as commercial nitric acid by mass in aquous solution. by mass look at the details in aquous solution study the question I'll give analysis of it aqueous solution slowly understand it solution what should be the marity what should be what should be should be the marity what should be the marity Huh? Of such a sample of such a sample.

[00:25:09]Such a sample of the acid of the acid. Similar type of the problem of the acid. If the density if the density of the solution is 1.54 g per ml similar type of the problem take some 2 3 minutes try to solve the problem good morning where is your friend You invite your friends from the school college to join. See many students face a difficulty in solving competitive exam questions because they directly go to try to solve the competitive exam problems without actually completing the NCERT text.

[00:26:14]You solve it. See the hint I will give you. You take some 5 minutes and solve.

[00:26:20]First of all collect the data metric. What we are asked to get? What is asked? You collect it first. Then you can prepare. What is asked? Marity. What is the formula of marity? Marity is equal to number of moles of the solute.

[00:26:39]Carefully note down divided by volume of solution number of moles of solute. What is the solute?

[00:26:55]is 68% is nitric acid. Given the meaning 68% is nitric acid nitric mass of mass of HNO3 is equal to how much? 68 g.

[00:27:25]Mass of water to the remaining mass will be mass of water 100 minus 68.

[00:27:32]100 - 68 it will be 70 32 g. Okay, we'll keep it ready. Mass of the nitric acid you got.

[00:27:42]First you want to get the numerator.

[00:27:44]Have this have like this. First you clear the numerator. Number of moles of HNO3.

[00:27:50]To get number of moles of HNO3, the formula is mass of HNO3 upon molecular weight. You have to calculate molecular weight of HNO3. How can you get molecular weight of HNO3? Hydrogen 1. We have not given nitrogen 14 plus 3 atoms of oxygen 3 into 16 you get 15 + 16 3 are 48.

[00:28:14]Add them 58 63 g. Okay. 63 g.

[00:28:20]Now you calculate number of moles. What is the mass of the nitric acid given to you? 68 divided by molecular weight of it is 63.

[00:28:32]Divide 68 by 63 you'll get number of moles of the nitric acid. Easy question but you have to practice it. 68 upon 63 you'll get use. You can use calculator 1.0 079 1.0 0 7 9 up to three decimal places sufficient and the numerator problem is solved now right then what is your aim now you have to get the volume of the solution in liter no volume any information is not given except density this is going to help you what is the density is given by mass divided by yes volume mean density of the solution is mass of the solvent divided by volume of solution. You you cross multiply take volume of the solution here because we are interested in volume of the solution divided by mass of the solvent divide by density. What is the mass of the solvent? Sorry, mass of the solute I'm sorry mass of the solute. mass of the solute because you are given with the density of nitric acid in a gram per cc which is mass of the solute is how much here 68 g divided by it is milll means it is given in cc that is 1504 no problem only you have to calculate 68 68 8 divided by 1.504 504 volume is 45 you can take up to two decimal places I will take 21 uh uh three round it up to three using calculator this many ccs you will get then volume of the solution in a liter we want in a liter means you have to divide it by th00and that is 45.213 213 divided by,000 liter 1,000 cc means 1 liter 45.213 conversion factor is divided by,000 you will get 0.0 how many zeros? Three places 0 45 213 liter or you can take just three decimal places 0.452 452 liter they will check your answer up to three decimal places.

[00:31:10]Now the problem is almost completed.

[00:31:13]Follow me you got what is the what is the marity formula? Marity formula is the number of moles of the solute already here solute what is the number of the moles of the solute you calculated number of moles of the nitric acid is 1.079 079 here it is number of moles of the solute we already calculated divided by volume of the solution in liter it is ready here which is 0 04 52 just divide it you will get the m marity 1 079 divided by 0.04502 04 52 you get 23 87 1 molar molar generally it is called as molar mality is called as mal just replace R by L so that is answer check for any mistakes Clarify doubts.

[00:32:57]the solution in liter. We checked it again.

[00:33:01]Volume of the solution in liter volume of the solution.

[00:33:14]Okay, sorry. Again, you have to take uh density is equal to number of solution.

[00:33:20]Sorry mass of solution you have to take instead of 68 you have to take solution 100 here there is a small mistake you correct it 100 upon 1.534 volume in liter volume in liter mass of the solution you have to take in case of marity that is a mistake 100 divided by 100 divided by 504 you can get 150.4 4 150.4 by density is given as density. What is the density given to you? 1.504 1.504.

[00:34:01]Now you can get the volume in cc that is uh you have to take 100 not solute because volume solution is equal to mass of the solution upon density. Total mass of the solution is 100 g. Therefore, I took only 68. That was the mistake.

[00:34:18]Correct it. 100 divided by 1 504.

[00:34:25]It comes out to be uh 66 489 66.489.

[00:34:39]Now you get all of the solution in later as 0.066 066 49 you can take 0.06649.

[00:34:48]Now you can substitute that value that is um mality is given by 1.079 divided by value of the solution later will be 0.0 now it becomes 6649. Don't take only mass of the solvent. You take the mass of the solution because this density is for the mass of the solution you will get 1 uh 0 79 divided by 0 6649.

[00:35:25]Check your answer. It will be correct.

[00:35:27]16 22 mala. That is the answer. Verify your answer.

[00:35:34]This is what 2 to 8 and you can round it off to get the answer 1. When there is 8 greater than five, you can add one digit to the previous digit. Therefore, this is called as approximation. You studied in the first year, you'll get 1.16.23 molar.

[00:35:54]Clarify your doubts.

[00:35:57]Interact please don't keep quiet.

[00:36:02]Next problem.

[00:36:04]There are three or four more problems just how many problems are possible today I will solve remaining you try otherwise you ask me doubts next period we'll continue with the solubility theory part of it theory part is very easy according to me in this chapter any difficult area is there these conversions these conversions and numericals on it this first part is difficult so remaining part vapor pressure and elevation in boiling point depression in fusion those problems will be very easy you can comfortably solve but these conversions of the units of the concentration marity mality so these are the dangerous area therefore I'm focusing on this particular area see next problem 1.5 in your text a solution of glucosin water is labeled as Carefully study the problem. A solution of glucose A solution of glucose is labeled as is labelled as is labelled as 10 percentage. Carefully note down W bar W means mass mass percentage.

[00:37:27]What would be the mality?

[00:37:30]What would be what would be the mality?

[00:37:39]What would be the mality and mole fraction?

[00:37:44]This area according to me is not easy area. This you practice more then this area mole fraction. What would would be the mality and mole fraction of each component?

[00:37:59]Of each component of each component of each component in the solution of each component in the solution.

[00:38:16]If the density of the solution again similar type of the problem. If the density of of the solution carefully read the word solution therefore you must not take the solvent solution is 1.2 g per ml.

[00:38:44]Then what shall be marity of the solution? See what shall be make this area perfect. What shall be huh marity of the solution? Marity of the solution.

[00:39:03]Okay. Again similar type of the problem.

[00:39:06]Good question for three marks.

[00:39:09]See you have to find out the three values. First of all you study carefully the problem. Read word by word what is given to you.

[00:39:20]A solution of glucose is labeled as 10% W bar means what? Mass of glucose is equal to you collect the information. Mass of glucose. Whatever information is possible you collect them. Mass of the glucose you know the formula of glucose is C6 est6 is 10 g then what will be mass of water in it?

[00:39:50]Total percentage means you are taking for 100 water S2 is 100 g.

[00:39:59]So number of moles you have to calculate will finish that area. See for that you you need molecular weight of molecular weight of glucose. Calculate molecular weight of glucose C6. There are six carbon atoms. Atomic weight of carbon is 12 12 into 6 + 1 into 12 + 6 + 6 into 18. I think you get 180. Remember it. I I'm showing you 12 6 are 72 + 12 1 are 12 18 5 are 90 1 8 you can calculate now 8 + 2 10 10 18 what is atomic weight of sorry 166 atomic weight of oxygen is 16 6 96 6 + 2 8 + 2 10 carry 1 9 + 1 10 + 1 11 + 7 is 180 g.

[00:40:58]Then similarly molecular weight of water you calculate basic things. Molecular weight of water. Water you know it is 18 g because oxygen 16 + 2 18. So number of moles of water first glucose you find out number of moles of glucose. Glucose mass of glucose upon molecular weight of glucose.

[00:41:24]What is the mass of the glucose? Mass of the glucose is 10 g. Molecular of gluc glucose is 180. You will get number of moles of glucose as you just divide 1 by 18 1 divided by 18. Your answer will be 0 55 recurring you can take 056 up to three decimal places. Number of moles of water will be what is the mass of water in it? 90 g. Molecular weight is 18 18 1 are 90. Therefore you get 5 moles.

[00:42:06]This is 0056 mole 1 by 80 correct. Now you go for solution case one what you asked mole fraction of each component in the solution. If the density is also given what is the density is given 1.2 g per ml of the solution.

[00:42:34]density of the solution. Okay, no problem. First, what you are asked to calculate? You have to note down what is asked. Very important. After noting down what is given, what is asked? You are asked to get what? First one what you are asked.

[00:42:51]What would be the mality? Small M.

[00:42:55]Second part is asked is mality and mole fraction. Mole fraction of glucose, mality of glucose solution. Third one is marity. All the three are asked. First of all, we'll start with the marity.

[00:43:16]What is the formula of marity? Formula of marity is given by number of moles of the solute.

[00:43:25]Isn't it?

[00:43:29]And the mass of mass of solvent.

[00:43:33]Am I correct? In K.

[00:43:36]Mass of the solvent in K. What is the mass of the solvent here? Mass of the solvent is solvent is water. When it is 10 g, water will be 90 g because percentage. When the mass of glucose is 10 g, mass of water will be 100us 10 which is 90 g.

[00:43:58]90 g mass.

[00:44:02]Now, number of moles of the solute, you already prepared it already here. But what do you need? Math of the solvent in kg. Kg means you you shift decimal point through three places to the left. You get 0.090 kg.

[00:44:21]0.090 kg. Now you can easily calculate mality number of moles of the solute is 0.056 divided by mass of solvent in kg. What is the mass of the solvent water 90 g in kg? It is 0.090 divide it you'll get the answer that is 0.056 divided by 0.090 090 you'll get 0. Number of mality is equal to 0.622 mal.

[00:45:01]Check your answer.

[00:45:04]First part is completed.

[00:45:07]Then you are asked to get marity mole fraction of glucose. Very easy. Already we are you have prepared.

[00:45:15]I hope you understood this one. If you got any doubts you can got it. Okay.

[00:45:21]Next you just interact. If you get any doubts you can stop me and clarify the details. Second part you are asked is mole fraction of glucose is given by number of moles of glucose G divided by total number of moles number of moles of glucose plus number of moles of water.

[00:45:43]Already we have prepared it. Mole fraction of glucose is given by number of moles of glucose is 0.056 divided by 0.056 + 5. You can easily get the number of mole fraction which is K not X will be 0.056 divided by 5.056.

[00:46:11]Five is whole number. Just divide it.

[00:46:14]You will get the mole fraction. Very easy. Don't worry about numbers.

[00:46:18]Whatever numbers maybe you can calculate. 0.056 divided by 5.056.

[00:46:27]You'll get 0 0 1 1 0 is there. You can take it as 1 m. Sorry, small mal.

[00:46:39]It should be read as M O L A L 0.0111 0 1 1 no it's a fraction no unit sorry no unit more fraction is 0.11 let me r this question part so that I can calculate the third one all details are ready now but many students do mistakes while getting marity see marity formula carefully number of moles of solute already ready that of glucose divided by volume of the solution in kg. See the difference between mality in marity you are taking mass of the solvent in kg in marity you are taking volume of the solution in kg already numerator is available what is the value got it already 0.056 0 5 6 we have to fill in this gap the solution in kg given density third time I'm showing you so density of the solution is given read the question already you collected I rubbed it what is the density of the solution so density of the solution is 1.2 2 g per ml.

[00:48:00]You know the density formula.

[00:48:04]Density formula is given by density of the solution is given by that is mass of solution very important divided by volume of solution.

[00:48:17]Density of solution is you can write take volume of the solution to the left.

[00:48:22]Then you get the total mass of the solution.

[00:48:26]Mass of solution not the solvent or solute upon volume of the solution upon density of the solution you have to write. Now you can easily get the values right. What is the mass of the solution is 100 divide by density of the solution is 1.2.

[00:48:49]Just divide 100 upon 1.2 you can get the answer.

[00:48:57]100ide by 1.2 1.2 to you will get the answer 83 83.33 ml milll means cc cm cube but we want it in liter okay let me rub this part we are in the last part anyhow we want it liter to convert it into liter divide by divide divid by 100 83.33 divide by that is 0.0833 0833 liter you can take. Now you substitute the fill in the blanks. What is the volume of the solution? Volume of the solution in kla. Marity in a liter that is marity is equal to number of moles of the solute upon volume of the solution in liter. Volume of the solution in liter we got it as 0.0833.

[00:50:06]Just divide it you will get the answer.

[00:50:10]What is the answer?

[00:50:13]0.0 divide using calculator simple calculator 0.056 divided by 0833 you'll get 0.672 molar is the answer. Thus we got all the three that is mality, marity and mole fraction. I hope you understood them right. I will take another little bit difficult question 1.6.

[00:50:52]Any doubts in this? You can ask me doubts.

[00:50:58]Ask me doubts.

[00:51:03]Okay.

[00:51:04]Fine, we continue with the next problem.

[00:51:09]I hope you understood this one. If you not understood, you just rewind it again.

[00:51:16]You can understand it better.

[00:51:20]Next 1.6 in the textbook.

[00:51:24]How many ml of carefully solve? Very dangerous question. How many ml of means cc will you cc of.1 molar hcl are required are required take the problem study carefully are required to react completely with to react completely with completely with with 1 g mixture.

[00:52:13]Tough question. 1 g mixture of sodium carbonate Na2 CO3 and sodium bicarbonate and sodium bicarbonate NH3 containing equimar amounts containing containing equolar means number of moles are same equimar amounts of both amounts of both.

[00:52:52]So whenever you solve difficult problems in physics, chemistry statement problem in mathematics, first of all you have to collect the data given what you are given with the concentration of HCL is given molar concentration of HCL. We write it in a square bracket like this which is.1 m. What is the meaning meaning of it?

[00:53:19]Means 1 mole is mole in one liter.

[00:53:26]That is the meaning of it.

[00:53:29]Here are required how many how many cc that is the question we'll think of it. React completely with one gram of mixture.

[00:53:40]There are two compounds sodium carbonate better mass of sodium carbonate mass of Na2 CO3 plus mass of Na CO3 total mixture is 1 g. See the interesting thing and the number of moles of both of them are same. Number of moles of Na2 CO3 equimar. See the word what is equimar?

[00:54:20]Number of moles will be same. Number of moles of sodium carbonate is equal to number of moles of Na CO3. We don't know. Let us call it as X mole. Both of them are X mole equal. We don't know X.

[00:54:33]We have to find it out.

[00:54:35]Now what is our aim? How many ml of.1 MHCL is required? For that you have to see the reaction. Whenever carbonates and biccarbonates are treated with HCl, you must know to write the reaction styometry.

[00:54:51]See whenever sodium bicarbonate reacts with HCl, write the reaction. Reaction you write you will understand lot of things. HCl. Can you guess the product here?

[00:55:05]You can get the product as NaC Na Cl plus S2O affirmations are observed in the laboratory we studied in the 10 standard whenever any biccarbonates or carbonates are treated with biccarbonates or carbonates are treated with HCl what they form I'll give the hint analysis what it will form Yes, it will form it will form NaCCl and water. Then what happens? Balance equation. Na 1 atom 1 atom chlorine 1 atom 1 atom carbon one atom 1 atom oxygen atoms are three 2 + 1 3 hydrogen atoms here is one here is one. No need not balance it. Means one mole of sodium bicarbonate react with one mole of HCl.

[00:56:04]Remember the react reaction we are not worried about products. Similarly we take sodium carbonate plus HCl. What is the product? Again you are getting you are getting NaCCl plus H2O plus S2 plus CO2. balance equation you can get now Na2 2 NaCCl write the equation I will tell you and if you attempt such problems your mind will will be set to the type of the problem then you can attempt the multiple choice questions carbon carbon then you go for shortcuts 3 2 + 1 3 Now see here 1 mole of sodium carbonate always reacts with water to completely react you need water two mole of it.

[00:56:56]I hope you got it. Now what is our asked now? We'll go for asked.

[00:57:02]What you are asked? Very important question. Not easy question. How many milll of means volume in CC? volume in CC of HCl is required not to completely react if both of them contain equar amounts of the both. Now how do you solve this?

[00:57:33]Are you getting me? So it requires little more discussion. Tomorrow I will next period I will continue. You try continue try this right because uh we cannot finish it within 2 3 minutes already time is up.

[00:57:49]So next period we will continue the remaining part of it you just study it along with that we'll finish this particular area by solving 1.6 6 problem I will I'm solving if you solve 1.7 two more problems you will solve then you study solubility next topic solubility in the next period and I will start discussing the theory part of it understand theory first then very important thing is in physical chemistry in this particular solution is from electrochemistry and solution are from physical chemistry physical chemistry will have numericals in organic and organic Chemistry is very easy. If you study it, you can manage it. If you remember it sufficient. But here you need lot of applications. See the textbook problems you solve first.

[00:58:39]If you are perfect in textbook problems and how to calculate marity, mality, mole fraction, right? Without confusion.

[00:58:47]Now try this one. Think about it. I will continue in the next class. Right? And uh um QC2 response is very low. Many of you are not coming in the live stream and particularly I'm working in the morning hours for PC2 students only creative because no other time is left evening all schedule is packed in SLC PC1 state CBSC IC therefore only option is morning and therefore you watch it and join the WhatsApp group you at least if you like the classes you bring students if you come on live start interacting like the 10 students are interacting wonderfully. IC students are interacting wonderfully. PC and PC students are not serious. Please u join your friends. Ask them to come to the live stream and let them interact. More you interact more interest I will get to teach you. That's all my dear students.

[00:59:49]We'll continue tomorrow same time with the mathematics inverse trigonometric function. This month I have got three chapters to cover two chapters in uh this in detail solutions and electrochemistry. Two chapters three chapters in mathematics one is inverse trigonometric function.

[01:00:10]first chapter second chapter matrices three chapters I'm covering this month already we are covering ITF and monthly monthly chapters will be covered on that we'll have multiple choice question test we'll have um appeared questions in katica CT g that then you can solve once the concepts are clear I'll go systematically step by step that is the only way systematic way is the only way of learning if you jump any uh any thing then you will be put in trouble directly you cannot build the third floor step by step you will go first learning should be slow and perfect give its own time take your own time depending upon your capacity and solve that's all for today my dear students download vims app my practice mind maths okay bye-bye see