 Okay. Okay. So let's start from pH. We all know very basics of the pH, right? What does it mean? The power of hydrogen ion, correct? Potens. Actually, the pH word comes from the potens, right? That is the German word and it means power, power, power of hydrogen ion. Okay. What is like pH? What, what is the, how, what is the significance of pH? So first of all, we have a scale which is known as pH scale, right? And it clearly tells us about the characteristics of the solution, of any solution. Okay. This is scale measures 0 to 14, 0 to 14. If suppose we have pH from 0 to 1, which we are going to discuss in further few slides, if we have pH 0 to 1, then it is, sorry, 0 to 7, then it is what? Then your solution is acidic, right? Then 7 to 14. Solution is all a base. Guys, please don't unmute. You can send me your answers in chat box. Okay. And don't worry. We have a very long class. We are going to discuss so many questions. So be ready for answers. Okay. Be ready with your answers and everything. But please don't unmute right now. Okay. Now, pH 7. If suppose we have pH 7 for our solution, what does it mean? That is neutral. The best example of neutral solution is what? Water. Correct? So pH we have in the form of pH scale, pH paper, right? pH paper, which we dip in the solution and then according to color, we decide the solution is acidic, neutral or basic, right? That also we are going to discuss. pH paper is a paper which is used to measure the pH or which is used to identify the nature of, the nature of solution, right? Okay. Next. Now, important thing, the strength of acid or base. So we know very well, we have a strong acid, weak acid, strong base, weak base and all those things, right? What does it mean? Strong acid gives raise to the more H plus ion, correct? Or a strong acid dissociates completely, almost completely. For example, HCl, H2S4, HNO3, but weak acid give raise to less hydrogen ion. Or I should not say that give raise to less hydrogen ion, but weak acids are what? Weak acid, that means if you have less hydrogen ion in your solution, that means the particular acid that is weaker, right? The best example is what? Acetic acid. The formula of acetic acid is CH3COH and carbonic acid. Okay? Next. Strong base, the same thing if your base dissociates almost completely. Now, you must be thinking, ma'am, what does it mean by almost completely? What is the extent of that? So it dissociates almost 99%, 99.9% also it's possible. Okay? So that means a strong base and weak base, that means just approximately 10%, 10%, 12%, 15% like that, okay? Approx values. The example of weak base is what? Ammonium hydroxide. Okay? Now let's discuss the pH of saliva and lemon juice and some cold rings, carrot juice and all those things. Now, here I need answers from you. What is the pH of saliva before me? What is the pH of saliva before me? Aryan tendon, very good. 727.5, okay? So, approximate pH value I will write here, 7.4. The pH of saliva before me is good. Okay, Akshita. Akshita Navya, yes, 7 or something. Yes, it's approximately 7.4, okay? pH of saliva after me, 527. Aryan is saying 527, okay? 527, isn't it a very big range? On Rila, I'm pronouncing your name correctly, isn't it? Less than 7, what I know. Okay, okay, thank you, beta. So, yeah, obviously, yes, yes, it's less than 7 beta, but you have to be give me the approximate value. Aniket, Aniket Gupta, you there? Aiden, what is the pH of saliva before, after me? Akshita, very good. Akshita, sorry, Akshita, very good. Aiden, Aryan, Shavita is there, Momita is there, Neha, Aryan, is it Aryan Mehta? Aryan, are you Aryan Mehta? Okay, beta. Yes, good guys, correct. So, pH of Arushi, good, very good. pH of saliva is what? 5.8, okay? It's 5.8. Obviously, the nature of substance would be what? Acidic, right? Okay, next, the pH of lemon juice. I'm talking about pure type of lemon juice, okay? Meghana, okay, Aryan, okay, Ralph, okay, Ralph is more about to correct. Meghana is also correct, okay? Neha, okay, okay. Sarita, okay. Ranjini, Ritika, Momita, yes, okay, guys, yes. So, the pH of lime juice is 2.5, approximately 2.5, okay? Now, guys, you have to do this table because it is in your NCRT textbook, right? So, you have to learn all these pH, okay? So, don't get confused. You can write approximate value, but try to be more perfect, okay? Try to write more perfect. So, instead of just 2.3, you should write 2.5, okay? Yes, Surya, beta, it's very necessary. It's very important. You have to memorize it. Lime juice, pH, they have asked in past year question. Tomato juice, pH, they have asked in past year question. One molar, NaO is they have asked in past year questions, okay? That's why I have included this table from your textbook. The same table is given, I guess, the pH number 26, if you've seen on the same table is there, okay? So, whatever you have in your textbook, we have to do, okay? Yes, nice. Akshita, correct, okay, Momita, yes, correct. Next, what we have, colorless, colorless, what? Areated drink? Colorless, areated drink, fine. What is the pH of colorless, areated drink? It's, I'll just give you one clue, okay? It's slightly acidic. No, no, Meghna, it's 2 less beta. No, it's slightly acidic, I'm saying, slightly. No, no, no, no, no. Think, think and answer. Very good, very good, Surya, Akshita, Anjaliya, correct. It's, yeah, 6 you can say, 6, okay? The pH of, pH of what I was saying, yes, pH of colorless, areated drink is approximately 6, okay? 6, 6.5 is fine, okay? Yes. Next, carrot juice? My son loves carrot juice. Okay, what is the pH of carrot juice? Again a clue, carrot juice is also acidic. Not the one which we drink, okay? The sort of more purified sample. It is also acidic, not very strong, but medium to weak acid. Carrot juice pH is 5.6, okay? You can write 5.5 also, no problem. 5.6, wait, I have written 5.5 once again. Yes, okay? Coffee, coffee pH 5, no, no, Meghna, it's 2 less beta, no. Coffee is also acidic, no, no, no. Coffee is acidic, guys. Yes, it's pH is 6, okay? Approximately 6.5 is also fine, no problem. So the students who have recently joined, please take the screenshot of this table especially, okay? If you have not written all of these things done, then please take the screenshot, okay? Yeah? Okay, next we have tomato juice. Tomato juice is slightly acidic. Moderate to moderate, moderate acid, I should say. Oh my God, Akshita, you have learned all, huh? Good, very good. So tomato, not tomato, tomato juice is 4.1, good. Then we have tap water. Tap water pH is neutral. No, 7, correct, Meghna, it's slightly acidic to neutral, okay? So tap water now you can write somewhere in between 6.9 or 7. Wait, coffee is 5.6. What I have written, once again, huh? Coffee is 6 actually. And tomato juice is 4.1 and tap water is 6.9. You can write 7, no problem, okay? Okay, now next we have NaOH. NaOH is a strong base, one molar NaOH is very strong base, very strong base. What should be the pH? Momita, right. Akshita, correct, very good. Saloni, yes, fine, correct. Surya, correct. Okay, so guys, listen, if you see one molar NaOH or one molar HCl, one molar H2SO4, okay? 1M, this means the concentration, okay, molar concentration. Molar concentration, okay? So one molar NaOH, one molar HCl, whatever acid base, if it is available in this amount, that means they are talking about very strong acid or a strong base, okay? Okay, so NaOH pH is 14 and one molar HCl pH is Meghna, oh, very good, good, good, zero, zero. Saloni, betide zero, okay? Ananya, Namesh, yes, Ranjini, Ghosh, good, zero, okay? Arendh Gupta, are you there in the class? Ishika Patidhar, correct, Rithika, correct, Vaishnav, correct, good, correct. Surya, where they have given, are they given, have they given one molar HCl? I'm under the heading gastric juices, it says it's about 1.2. Okay, okay, now listen, gastric juices little bit diluted, okay? So pH has slightly increased, slightly increased, okay? The one molar, that's why they have given the special concentration in your textbook, one molar HCl, the pH of one molar HCl is zero, okay? If you little bit, if you dilute it to what will happen, the hydrogen ion concentration will decrease, then pH will increase, okay? Yeah, okay. Arendh, please remind me to discuss this out better in the end of this class, okay? Because this is not related to our, what should I say, the CBC portion now, so I don't want to waste the time right now, because you know, we have so many slides remaining, okay? So please remind me in end of the class, don't forget. Okay, next we have pH scale. Now we all are very well aware of the pH scale, then why I have included this? You know, why? Because I just wanted to show you the colors, okay? See, if you have neutral one second, yeah, some student want to come, but it's not, he's not able to join, what's happening? I don't know. Just give me a second bit, okay? So why I have included this pH scale, just wanted to show you the colors. If you have very strong base, then what do you have to, what do you, what will be the color of the strong base? It's approximately blue, dark blue, right? Dark blue. If you have a strong acid, then the color of pH should be orange red, or reddish orange, okay? Okay? And if you have neutral, then it should be pure mehndi green color, I should say, okay? Right? So in the upcoming slides, we will see some questions which have came in 2015, 16, 17. I don't remember the exact year. You will see they're asking about the color of the pH paper for maybe NOS solution or I don't remember exactly which solution they have given. If the color of pH people you are getting very dark blue, that means the solution is sodium hydroxide, okay? Solution is sodium hydroxide. If the color of pH people you are getting orange, orange to red, that means that is your gastric juice or H2SO4 or HCl, okay? Okay? So need to keep that thing in your mind very clearly, very carefully. Next. Okay, next we have pH of solution or pH of solution. Instead of that, I have to write importance of pH in our everyday life, right? So you know in our stomach, stomach produces hydrochloric acid, right? It helps in digestion of food without harming our stomach. True, right? What is the reason how HCl can't harm our stomach? Very good, Meghana. Correct. Because of the mucous layer, right? We have a thick layer of mucous. Yes, yes, correct. Good guys. So when the stomach produces too much of acid, it causes pain, right? Pain, irritation, feeling of like burning sensation, okay? So this stage is called acidity. To get relief from this pain, what doctor suggests us to take anti-acids, right? Or to take that enol, because enol contains sodium bicarbonate, correct? Sodium bicarbonate is also basic. It gives us relief from the over acidity or acidity, I should say. So, so doctor prefers us to take the anti-acid. Any example of anti-acid? Jealousy. Jealousy is fine, Surya, but I need the content, content of jealousy. You guys know, I don't tell me. Aniket. Yes, yes, guys, correct. Milk of Magnesia or MGOH twice, okay? Milk of Magnesia or MGOH twice, correct? Milk of Magnesia, MGOH twice, aluminum hydroxide, those are the example of, okay, example of anti-acids, correct? NaHCO3, sodium bicarbonate is also the example of anti-acid, correct? No problem. Okay, yeah, magnesium hydroxide, guys, oh, I forgot it's written here only. Yeah, so magnesium hydroxide, this is known as milk of Magnesia. This is a mild base and also used for the, for this purpose, which purpose for, to reduce the acidity in stomach, correct? So pH of acid rain, pH of acid rain, you know, when the first rain comes after that winter, no, after summer season, yeah, after summer season. So that rain usually it is, it is, I have heard that that the rain is acidic rain, right? Because the rain, the water of the rain reacts with atmospheric pollution. What kind of pollution now? Atmospheric gases like sulfur dioxide, carbon dioxide, okay? And it converts into sulfuric acid and carbonic acid, and even nitrogen dioxide also, not carbon dioxide because that is not that much reactive. Okay, nitrogen dioxide, sulfur dioxide, and it, it converts into nitric acid and sulfuric acid, okay? So which gets mixed with the rain water and reduce the pH of water up to 5.6. So if the pH of rain water decreases up to, decreases less than 5.6 or up to 5.6, that is known as acid rain, right? Acid rain, 5.6 is acid rain, called acid rain, okay? So when, when this acid rain flows into the river or into the soil, what will happen? It will definitely going to affect the aquatic life, right? Aquatic life, plant life, because the body of aquatic animal also can survive at the normal pH. They have certain pH range, okay? They can't survive in acid pH, acidic pH, okay? The same thing is applicable for plant as well. We will see in the next slide. Yeah, it's here, correct. The pH of soil, a pH of soil and plant growth, yes? So the soil with higher peat content or iron content, like iron minerals, okay? Or with higher, with high rotting vegetation tend to become acidic. The soil which has higher peat content, iron mineral rotting vegetable content. So the pH of soil will decrease, okay? It will become acidic. One second, somebody move. Yeah, yeah, it will become acidic. So it might fall even less than four, okay? So this acidic effect can be neutralized by, by liming of soil, right? We have learnt it, correct? So this acidic effect of the soil can be neutralized by liming of soil. What does it mean? We can add calcium hydroxide or calcium oxide or powdered chalk into the, into the soil, okay? Which will increase the pH of soil and it will be maintained approximately seven, right? Okay, now if suppose by mistakes, any farmer has added too much of lime, then what can we do too much of this calcium hydroxide powder? Then what can we do? Add vinegar? Okay, good option you have given but Akshita, yes, correct, correct. Yes, so if the pH of soil raise to 8.3, okay? Then what can we do? We can add some organic matter. Even it is up to 8.3 also it is not acceptable, okay? So this can be reduced by, reduced adding organic decaying matter or decaying organic matter. Guys, is this pen colour fine? Is this colour of pen fine? Decaying organic matter, okay? So which, which reduces this is what should I say? This is acidic in nature, so it will reduce, it will maintain the pH of your soil, okay? Next, are body functions in between the pH range of 7 to 7.8, okay? In living organism and you know this is very narrow pH range. So we have to also, we also have to maintain the pH approximately 7 to 7.8, that is again another significance of pH, right? Okay, now this is very important point, the tooth decay and pH, how tooth decay is related to pH? We all know very well that the calcium, sorry the teeth enamel is made up of insoluble calcium phosphate, teeth enamel is made up of insoluble calcium phosphate, okay? Which is very hard, which is quite hard. So when pH of mouth falls below 5.5, the enamel gets corroded, the enamel gets corroded, it reacts with acid and then get dissolved into the acid, okay? So the bacteria present in the mouth break down the sugar to lactic acid that also increases the pH of, that also increases the acidity of mouth, right? And the formation of these acid causes decrease in pH, right? So that is why it is advisable that whenever we eat food, whenever we eat some sugary food or something, we always have to clean our mouth, okay? So that bacteria cannot degrade sugar and they cannot convert sugar into lactic acid. So pH of mouth should be balanced, right? It would be balanced then. Yeah. Now, how can we prevent it? How can we prevent tooth decay? Simple by using toothpaste after each meal or after having sugar, after having some chocolates, right? Yes. So the toothpaste contains some basic ingredients, basic ingredients which helps neutralizing the effect of acid and also increases the pH of mouth, okay? Right? Aryan has asked me one question, is the calcium salt formed as the result of neutralization or to use as plant? Okay, no, Aryan, basically why we are using calcium hydroxide or the basic content because it reduces the H plus ion concentration in the soil, okay? It reduces H plus ion concentration in the soil. That's our aim. Oh my God, gypsum? Seriously? No, no, Neha, gypsum is very less reactive. We can't use it, okay? When we will read that gypsum reaction and all that, and then I'll explain this question, okay? Yeah, next. Beasting or stinging, stinging hair of nettle leaves. What they do? They inject methanoic acid in our skin, right? Which cause pain, irritation, correct? So when we use weak base like baking soda, so we'll get relief, correct? That means what? Beasting or the hair of nettle leaves, they contain methanoic acid. Methanoic acid is also known as formic acid, right? Formic acid. So don't get confused. Okay, yeah. Aryan, is there particular reason though? Yes, beta because the reactivity, okay? The reactivity of calcium hydroxide is important. Okay? So once we discuss the gypsum thing now, we will discuss why we are using lime or that calcium hydroxide, why we can't use gypsum, okay? Yeah, next. Yes, you know what the hair of nettle leaves contains methanoic acid, correct? And then this plant is actually have seen in the wild areas, correct? You know, if suppose you get touched by this plant or the hair of this plant, definitely you are going to feel irritation. What is the solution? In the that wild area, you are not going to get sodium bicarbonate. And suppose you don't have sodium bicarbonate, then what will you do? Yes, Surya, doc plant, correct. So nature itself has given the solution to us, right? There is a traditional remedy is rubbing area of that pain area with the leaf of doc plant, which often grows beside the nettle plant, okay, in the wild area. So why? Now, what is the contained of doc plant? Like what does it contain? Obviously, because it is neutralizing the effect of methanoic acid, that means the doc plant containing should be containing some base, right? Basic ingredient, okay? So doc plant contains a basic ingredients, which helps to neutralize the formic acid, okay? Yes, please read this thing properly, okay? This is also given in NCRT textbook only, but I don't remember the page number. Now we have a question, very easy question, right? 2012 and then repeated in 2014, write the name of given, sorry, write the name given to bees that are highly soluble in water, waiting for your answer? Correct, correct, correct. So water soluble bases are known as what? Alkali? Very good. Guys, only alkali is not enough, okay? Alkali is the answer till here. Given example, you have to write example, either KOH, any of these, anything is fine, okay? Yes, yes, you have to mention, otherwise definitely you're going to lose half ma. This question is for three ma, okay? Water soluble bees, what I was talking about, yes, water soluble bases are called alkalis, example, NaOH, KOH, okay? Next, how to decay related to pH? How can it be prevented? So this was the answer for A, now for B. You can write in short if you want. Yes, yes, correct, correct, correct. Oh my God, Aryan Tandon, very good speed, good Shabita. So how to write it and what are the keywords? Tooth decay starts when the pH of mouth gets lower than 5.5, okay? So tooth decay starts when the pH of mouth decreases or when the pH of mouth is lower than 5.5, right? What is the exact question? How tooth decay is related to pH? Okay, yes. Now you have to mention, see how tooth decay is related to pH, right? So here you have to mention the, what should I say, tooth decay starts when the pH of mouth is lower than 5.5, why? Because in the aesthetic medium, the tooth enamel starts corroding, okay? Start dissolving in it. In the aesthetic medium, tooth enamel, what's happening? Guys, just give me a second, okay? Yeah, tooth enamel gets corroded. Varsha, very good, beta. It's corroded and causing tooth decay, very good, causing tooth decay, which can be prevented by, can be prevented by cleaning the mouth and teeth using toothpaste, using toothpaste. Okay, now cleaning the mouth using toothpaste is not enough, okay? Cleaning the mouth and teeth using toothpaste, preferably after each meal or after having sugary food, okay? After having sugary food. Done, right? The next question, next part of the question was, see I guess, yeah, why does bee sting causes pain and irritation, rubbing, baking soda, you know very well how to write, oh my, Aryan and Neha, very good, beta. Shobhita also nice to see your interest, good. Let me just go through bee sting, contains, methanoic acid causes pain and irritation, baking soda and nature. Very good, correct, correct. Yes, good guys, yes. So, we can write the same thing, okay? I'm just going to copy your answer only because it's absolutely fine. So, answer for C, okay? One more answer has came. Yes, bee sting contains formic acid or methanoic acid, formic acid or acid, okay? Which causes pain with pain or irritation. Rubbing baking soda on the bee sting area gives relief, why? So, the rubbing baking soda, baking soda is basic in nature. Baking soda is basic in nature, which neutralizes the acid, right? Basic in nature. So, it neutralizes acidic liquid ejected by bee sting. Injected, injected by bee sting, okay? Gives relief, okay. Good, very good. Next question. Mama, I have doubt, can I please ask before we move on? Manu, who's this? Mama, Akshita, I've messaged the doubt to you personally. Wait, I'll check Akshita. Akshita, can you please copy and paste again because I'm not able to see your message. It's not appearing in my phone. Akshita, okay. See, Akshita is asking one thing that non-alkali basis cannot be dissolved in water. How do we see their basic properties? Do they still produce OH negative ion? Very good question. So, Aiden, are you there? Aiden, are you there? Can you explain Akshita's question? Can you explain to Akshita for this question? Try, try. Aiden, I know that you know the answer. Yes, Aiden, I'm waiting. Are you in tendon? Do you have any answer for this? Are in tendon? Okay, Anjala, no problem. Okay. Wait, wait, wait, wait. I couldn't see the message. One minute. Where is the? Yes, shares, correct, correct. It's true. Okay. See, Akshita shares and all of you, please listen to me. See, basis only, they don't have only one property that they show OH negative ion. It's not like that if you have only H plus ion, then only it would be acidic. If you have only OH negative ion, then only it would be acidic. No. Okay. They have other more properties like, let's say ammonia NH3. You know what? When it reacts with water, what happens when it reacts with water? It takes H plus ion from water. So, what it is forming NH4 positive. Now, what it is giving in the solution, what it leaves behind NH4 positive and OH negative. Again, this the presence of OH negative indicates what basic characteristics of this ammonia solution, right? Okay. So, because they neutralizes the acid, they, that's why they are the base. Okay. They are not only the base, they because they have OH negative ion. No. Or they are not only the base because they produces OH negative ion, right? So, the important definition, what do you need to keep in your mind that basis neutralizes acid? First thing, second, base accepts proton. If they accept proton also, that means that is a base. Okay. Or if they donate electron, that means these are the bases. Okay. No, no, no, Anish, who told that they have to be dissolved? They have to dissolve sheets and pill. Okay. Like, let's say any metal oxide. Okay. Which oxide you will take calcium oxide? How does it form calcium? Why calcium oxide is a base? Because calcium oxide forms calcium hydroxide, which after reacting with water releases OH negative ion, right? So, the calcium oxide tends to tends to the formation of OH negative ion, right? And the basic the properties of the base is not only depending upon the release of OH negative ion. It depends upon two other things, right? INR guys and white people guys, if you remember that we have learned the theories, Arrhenius theory, Braunstein-Lawry theory, and one more is there, CHK guys, you must, you should also remember that, right? One more theory is there, which one Louis theory, which says that what all the compounds are bases. Okay. Yes, Anish, the non soluble basis, that means the base which react with acid to form salt and water. Those compounds will be base. If they don't produce OH negative, that is fine. Okay. This disassociation is not necessarily required in water. It can happen with acidic medium acid. Okay. Yeah. Good. Okay, let's do this question quickly. I hope you're done, beta. If still you have doubt now, you can ask this route in the Centrum Forum or you can ask me personally. Okay. If you are in the that student group, just post your doubt over there personally, I'll send you the some document related to this. Okay. Okay, good. Actually, you are not in the group. Then how are you getting the link from the learners? No, no, I didn't I don't know. I don't think she is there in the group, WhatsApp group in the moxtra also. Actually, that's from which school are you, beta? Yeah, I know. Okay. Okay, you're from DPS. Then how will you get to? Okay, then I will tell you the process of the posting doubt in the Centrum Forum. Okay, you can post it out in the Learnist. Okay, there's a separate doubt group actually. Yeah. Okay, good. But is this clear? Like what do you have asked? Is this clear now? Okay, guys, now let's see this question. The reason of following dry itself does not change color of the dry. Once again, something went wrong again. So many answers. My God, wait, wait, wait, wait, wait. I'm not able to see your answers. Good. Okay. Very good. All of you know the answer, yeah. Yes, dry ACL does not contain hydrogen ion in it. So it does not show any acidic behavior, right? Yes, good. Correct. So dry ACL does not contain. Okay, guys, meanwhile, you send me answer for the next one, alcohol and glucose. Okay, for that, you send me the answer. Okay. Dry ACL does not contain any hydrogen. So it does not show any acidic behavior, acidic behavior, and whatever dry ACL gas, dry ACL gas. Okay. Next. Alcohol and glucose. Excuse me. Alcohol and glucose also contains hydrogen, but do not conduct electricity. Yes. Oh my God. So many answers again. Good. Yes. Alcohol and glucose do not conduct electricity because because they don't dissociate into water, right? This was the question of 2014. 2014. Okay. Yeah. Okay. Disha. Sort of right. Okay, wait, I'll write the correct answer here. Wait. The eco solution of alcohol and glucose, a solution of solution of glucose and alcohol do not show electricity. Oh, sorry. Do one second. Hushri has entered. Yeah. Do not conduct electricity because because because because of the absence of free ions or absence of free electron because absence of free ions or free electrons. Okay. Now please pay attention. Equal solution of glucose and alcohol. They dissolve in water, right? But they don't dissociate into ions. That's why they don't contain, they don't conduct electricity. Okay. They don't form H plus ion. They don't form any other type of ion in the solution. So they don't have any free electron to move. Okay. Next. Concentrate concentration of extra positive ion is affected when the solution of an acid is diluted. So tell me the reason. Disha was ready with the reason. Good. Yes. Neha is also correct. Correct. Good. So how to write how you have to write this in the proper way. See here. Hydrogen ion do not exist in the solution independently exist as H plus ion in the solution. Because it's unstable, right? They react with the polar. They react react with with polar water molecule. Polar water molecule to form to form hydroneum ion, right? How does it happen? H plus plus H2O gives H3O positive, right? So when does when a solution of acid is diluted, the number of H3O positive ion per unit decreases, right? So when a solution of acid is diluted, the number of H3O positive ions per unit volume decreases, right? Decreases. That's pH of the solution. What does pH of the solution increases? Okay. Now what are the keywords here you have to mention? This this paragraph is very important. You have to mention in your solution, okay? Okay, next. Now you are provided with a three test tube A, B and C or maybe C, A and B, which contains distilled water, acidic solution and basic solution. If you are given with a blue litmus paper only, how will you identify the content of each test tube? The question was came in 2015. You have three test tube and all three test tubes are containing, sorry, each one of them are containing distilled water, then second one is acidic solution and the basic solution, right? So how will you identify the characters of the all the solution with just only one litmus paper blue? Any guys, any idea? Okay, I'm writing it here, okay? Okay. Yes, yes, yes, yes, yes. Correct. So the answer should be you can write in this way. The first we have to take three strips of blue litmus paper and deep one in each test tube, three strips of strips of blue litmus paper. Very good. Dip one in each tube, right? So the liquid in test tube A, the first one second point, the liquid in test tube A turns blue litmus to red, turns blue litmus to red, right? What does it mean? It means the test tube A contains acid, test tube A contains acid, why? Because acid turns blue to red, right? Blue litmus paper to red, A, B, R. Correct. If other two test tubes do not change the, do not show change in color. Now, if other two test tubes do not show change in blue litmus paper color, that means what both of them must be containing a base or neutral solution, right? Correct. I'm so a blue litmus paper dipped in a base, neutral solution will have no change. Yes. Okay, ma'am. Who was that? Ma'am, it was Meghna. Hi, Meghna. Your question was actually good. If suppose you have blue litmus paper, right? But if you put it into the neutral solution, then what will happen? It should change, it should show the change in color, right? Yeah, ma'am, that's what I thought. Yeah, no, no, that will happen only, that will happen only if you have a blue litmus paper, then it will show the change in color. Correct. So once if it is changing the color into red, that means you have acidic solution. If you're one litmus, sorry, one test tube, if it is showing no change in color, that means what we don't know which color is there, like which liquid is there, right? If the one which is showing, which is turning it into green. Okay, that means you have neutral solution. Okay, that means you have neutral solution. So blue litmus does change color. Neutral solution does change the color of blue litmus paper. All right, ma'am. Yeah. One, six, so many messages are there, ma'am. Wait, wait, wait, I didn't see your name. Aryan, actually you are right, they should write that respectively. Okay, but if they have not written, then you have to, like by default, you need to understand that the first one is having the first thing. C is having distilled water and A is having acidic solution and B is having basic solution. Okay, sometimes there must be some, what should I say, printing mistake, but obviously they are not going to consider it. We have to consider it, right? Okay. Yeah. Okay. So I think I have to correct it here. If other two test tube do not show change in color, no, no, no. If the one test tube, let's say test tube C changes its color from blue to green. Okay, that means what? It is your neutral solution. So I should write here means it is neutral solution. If you are the last test tube B does not show a change in color, that doesn't means it is only the basic solution. Okay, you have to cross check. How will you cross check? You can use this strip of test tube A, which has turned into red. Okay. So your test tube B will turn red color of that acidic litmus paper into blue. Did you understand what I'm trying to say? Okay. Guys, understood what I'm saying. Okay. Now, red litmus paper, paper in test tube B, if it is not showing any change in color, oh my God, I don't have enough space. If it does not show change in color of blue litmus paper. Okay. Now you must be thinking red. From where will you get the red litmus paper, the red litmus paper, red litmus paper turned red by acid, turn, turn, red by acid. Okay, turn red by acid. We have to put and then it changes from blue to from red to blue. Excuse me. Red paper changes to blue. Okay, which indicates gates, the presence of presence of basic solution, basic solution in test tube B. Okay. Ah, sorry, I don't have enough space. No, no, no, I didn't know it won't be purple in neutral solution beta. No, it will turn from blue to slightly it will turn to greenish blue. Okay. I mean, but that's universal indicator, right? That the universal ph strip we are talking about? Mom, you're talking about litmus paper, right? Oh my God, yeah, yeah, yeah, yeah, correct. Correct, correct, correct, yeah, correct. Sorry, guys, I forgot we are talking about litmus paper. I was just assuming the ph strip. Yeah, correct. I did that experiment with the ph strip, but here we are talking about litmus paper. Yes. So yes, correct. That's why the thing here what I have written if we if we don't see any change in color, that means because we are using litmus papers, it won't turn from blue to green. Even it won't turn blue to very like what should I say bright purple. The change in color to identify the change in color would be difficult. So again, you need to what will you find if you have two test tube C and B and if you're using blue litmus paper in the border test tube, then there will be no color change. Okay, so what do you have to do? You have to use the red strip that red strip which has turned red by the aesthetic solution in in test tube C also. Okay, so let's say you have two test tubes here, guys, sorry for the confusion because I even forgot that you're talking about litmus paper. Yes, here you have C, here you have a and here you have let's say B. So here we are using blue litmus paper. One minute, I'm not able to see your messages. Blue litmus paper, it will turn to red. Here also we are using blue litmus paper. And here again, blue litmus paper. Okay, but no color change. Here also no color change. Here also no color change. Yes, I will come to this point. Okay, so see no color change. Why I'm writing no color change here, because the change in color to identify the change in color is very difficult here. It doesn't change into bright purple color. Okay, if suppose because they have not clearly mentioned you with how much aesthetic solution do you have very strong weak acid bond. If you have a strong acid, then you will get the intense blue color, right? And blue and purple, that is not a very big difference. Okay, so you can't assume or you can't be very sure that C is containing the neutral solution. You have to cross check it. Okay, you have to cross check. Yes, Surya, one litmus paper is enough, but by any chance if it get wet, like very deeply wet, then what will you do? So be safer side, you have to take now. See when you have to take here, when you have to take here, correct? Then you found no change. Then you use the red litmus paper of this here. Okay. And again, no change. Then you use red litmus paper of this here. Then definitely here you will get change the red into blue. Right, Surya? Okay, okay. So yes, that was the good discussion done. Done with this question. Okay, good. Next. Now let's talk about salt. Yes, thanks for reminding me. We are talking about litmus paper. And I was assuming the universal paste strip. Next neutral salt. Okay, neutral salt. What do we? Sorry, salt. First of all, salt. Basically, what is the salt? Salt is what? Salt is the ionic compound, right, which dissociate to form ions, correct, ionic compound, which dissociate to form ions. We have different different types of salt. Sodium chloride, the like the neutral salt, then acidic salt, basic salt. So as neutral salts, neutral salts are usually formed by the combination of a strong acid and strong base. They have pH approximately seven acidic salt formed by the combination of a strong acid and weak base. Okay, they have pH less than seven, obviously, right? And basic salt is strong formed by the combination of strong base and weak acid, which has pH more than seven. Very common thing we all know very well, right? Let me just think what I have. I was thinking to explain you here. Any question anybody? Somebody was unnoted. No, okay. So yes, neutral salt, acidic salt and basic salt. In upcoming slides, we will see how to write the answer for to identify or to explain the acidity or basicity of the song. Okay, suppose if I am saying HNAHCO3, why NAHCO3 is a basic salt? How will you explain it? How can you tell me that? Yes, it is a basic salt. What is the reason? Okay, shares apart from this beta, apart from this any other thing? Arian, Anirudh, any other thing? How can you tell me that weak acid, weak base gives you neutral salt beta, neutral salt. Okay, the pH would be approximately seven, neutral salt. Yeah. Okay, I'm getting answers. Yes, yes. Any other, any other answer for this? Anirudh, are you there? Shobita? Momita, are you there? Okay. See here, I'm writing the answer and how you need to understand this question. Okay, how you have to write the answer for this type of question. This is what this is the salt of, salt of weak acid, what is that carbonic acid CO3 and, and strong base? What is that NaOH? Right, weak acid and strong base. Okay, you know what happens after dissociation. Okay, after dissociation in water or after reacting with water, NaHCO3 plus H2O. It forms Na positive, HCO3 negative plus water. Okay, now you know what happens? This HCO3 minus reacts with water. HCO3 minus reacts with water and it forms what? It forms carbonic acid again. So what it is giving? H2CO3 plus Na plus. What is remaining? OH minus is remaining? Correct. So see in end of the reaction, what do you have? You have OH negative ion concentration, right? OH negative ion concentration. That's why sodium bicarbonate is basic in nature because it produces OH negative ion in the solution. Now, what is the reason? The reason is the carbonic ion, what should I say? Yes, hydrogen carbonate, hydrogen carbonate hydrolyzed with water. Okay, HCO3 negative ion hydrolyzed with water, with water to produce what? To produce carbonic acid. Okay, and produce carbonic acid, OH negative ion. Okay, sodium ion does not, does not hydrolyze with water. Okay, so it doesn't hydrolyze. That means it doesn't form any OH. That's why you have OH negative ion concentration in water, which indicates the basicity of the solution. So presence of OH negative ion indicates basic character of NaHCO3. Understood? Everybody got it? Everybody got it? I just have received the message from Arian and Shreyas. And we are total 72 here, 72, 70 for something like that. So you understood the meaning of hydrolysis, right? If suppose I ask that CH3 why it is acidic, sorry, why it is basic in nature, how will you answer in the same way? Okay, here we are using carbonic ion, there you have to use acetate ion. Acetate ion gets hydrolyzed by water to form acidic acid. Okay, and it leaves behind OH negative ion concentration. Right? Okay, move into the next slide. Now we will see some important salts. The first one we have is sodium chloride. Okay, sodium chloride, you know, it's a very commonly known salt, common salt, correct? So first, what is the formula? Very well, we all are aware very well, right? Sodium chloride is NaCl. Occurrence of sodium chloride. Cool, so okay, okay. Yes, I was talking about sodium chloride. So it's NaCl, sorry, the chemical formula is NaCl. And common name, you know, common name. What is the common name? Caustic soda. Action on litmus paper. What is action on litmus paper? It's neutral, right? See, nobody's paying attention, right? Nobody's paying attention. I have written caustic soda, but nobody said that ma'am, sodium chloride is not caustic soda. Guys, what are you doing? You sleeping? Seriously? Is that the class getting very bored? Akshita? Okay, don't get confused. Be confident. Don't get confused. Okay, you guys are done with your pre-boards. You have learned everything. This is the additional revision for you. So you have to be confident in your answers, in your concepts. Okay, if there is any confusion, if there is something, I will make it clear. Don't worry, tell me but after a long time, I just got a message from Aryan about this caustic soda. Okay, so guys, please be aware and just refresh your mind and then sit in the class. If you want to go and just take a round of your house or your nearby area, just go. Take it and then come back. But if you are here, you have to be here with complete presence of mind. Okay? Okay, the common name. Common name of this is what? Rock salt or common salt. Okay? Common salt. The action on litmus paper, neutral. Solubleate in water. Highly soluble. Highly soluble. Right? Occurrence. It occurs. It occurs in seawater. Occurrence I'm writing here. Occurrence is important for you. Okay, it's given in NCIT as well. Occurrence, seawater. How much the contained, how much it contain? Almost 3% right? Approximately 3% of NACL. Right? Next, water of inland lakes like Sambhar Lake. Okay? Sambhar Lake. Where we can get this Sambhar Lake in Rajasthan. Where do we have it in Rajasthan? Okay? Rock salt is more with impurities and common salt beta Surya. It's not very different. Sambhar Lake in Rajasthan. Salt mines, right? Last is salt mines. Okay? Yes, done. Okay. So everything is mentioned here also. Next, important chemicals which we get from sodium chloride. So the first is sodium hydroxide. How do we prepare sodium hydroxide by the help of chloralkali process? The process to prepare sodium hydroxide commercially at the industrial purpose that is known as chloralkali process. See the name itself indicates chlorine and alkali. Okay? That means in the in this process, you get chlorine and alkaline solution in the end. Okay? Okay? So chloralkali process is because we get chlorine and a base as in the result in the product. Okay? Yeah. NaCl, what is this? What is the chemical reaction? Overall chemical reaction is what? NaCl plus H2O gives Cl2 plus H2 plus important compound NaOH. Right? If I balance it, then it should be 2 and 2. Right? Okay? So this is the chloralkali process. Now, you must have a diagram in your textbook but actually you don't need that diagram. What is the important thing here? You have to keep like you have to keep in your mind. You know, you get chlorine in this process, you get chlorine at anode and you get hydrogen at cathode. So what does it mean? When you pass electricity, when you pass electricity from the brine solution. Okay? When you pass electricity, electricity from the brine solution. What is brine solution? The concentrated sodium chloride solution. Concentrated sodium chloride solution. Concentrated NaCl solution. Okay? When you pass electricity from the brine solution, it converts into chlorine, hydrogen and right now chlorine we get it anode and hydrogen we get it cathode okay you know what on passing electric current through the solution of like a brine solution hydrogen ion discharge more easily at cathode hydrogen ion discharge more easily at cathode cathode okay as compared to what as compared to as compared to which more positive an do we have as compared to sodium okay right and there it gains electron it gains electron to convert into what hydrogen right so what is the reaction there what is the reaction do we have at cathode an anode the reaction at cathode and anode we have it's something like this H plus gains one electron to form H this H is unstable react with another hydrogen atom to form H2 right at anode guys I'm not able to see your messages right now so please wait anode H plus ion sorry at anode chlorine it forms right at anode we get chlorine so Cl negative reaches to anode first as compared to OH negative okay so Cl negative loses one electron to form chlorine chlorine reacts with one more atom of chlorine to form Cl2 okay that's how you get chlorine at anode and hydrogen gas at cathode now what is the remaining in your solution any positive and OH they both react together they both react together to form what any OH okay okay understood what is the use of any OH it is highly used bees right multi-purpose industrial process maybe use it and then what is the another important use information of soap and detergent soap and detergent okay any other question related to sodium chloride and sodium hydroxide related to this process chloralkali process did you understand okay now see the chlorine what we get from here we have different different uses of this chlorine the most important use of this chlorine is what the formation of bleaching powder okay so you know what the manufacturing plant of any sodium hydroxide okay you have if you have a plant of sodium hydroxide definitely that that manufacturing plant must be connected with the plant of bleaching powder okay our bleaching powder should be produced in the same plant why because all the chlorine produced in the process of sodium hydroxide can be consumed isn't it right right okay next see here the diagram this is given in your textbook as well hydrogen we get at cathode and chlorine we get at anode okay simple right this hydrogen gas we can use as a fuel okay in the formation of ammonia for fertilizer this chlorine gas we can use in PVC as in disinfectants but chlorine purely we can't use as a disinfectant we have to form bleaching powder and then we can use it as a disinfectant okay yeah and yes we use in water treatment as in the form of bleaching powder right so when this chlorine when it formed the chlorine right it's react it reacts with calcium oxide correct it reacts with what calcium oxide is it how do it form bleaching powder guys chlorine react with calcium hydroxide for god everything are the chlorine react with calcium hydroxide and it forms CaOCl2 okay calcium oxy chloride this is your formula bleaching powder we are going to discuss it okay next another important chemical is what bleaching powder right how do we prepare bleaching powder it is prepared by the action of calcium hydroxide with chlorine okay so you can say that bleaching powder can be prepared by the action of dry slag line dry slag it line with the action of chlorine gas which we are obtaining from the chloralkyrie process okay so it forms calcium oxide chloride and water this is your bleaching powder right line with chlorine we get from chloralkyrie process and it gives calcium oxy chloride so don't get confused by the name okay calcium if it comes in your exam also oxy chloride right okay what is it like how does it looks like what is the properties of bleaching powder have you seen it I think you must have used it somewhere it looks like yellowish white powder right yellowish very good iron yellowish white powder second what happens when we expose this into air what happens when it goes to air it reacts with carbon dioxide okay it reacts with carbon dioxide so CaOCl2 plus CO2 what it gives CaOCO3 CaCO3 calcium carbonate plus chlorine gas okay okay now yes very good iron very good correct good observation when we expose into air we get some chlorine smell right the smell of chlorine why because it gives chlorine after reacting with carbon dioxide it gives chlorine here I have written okay now important thing I'm going to ask what is the responsible for the bleaching action of bleaching powder which thing is responsible and okay what do you see that iron what is the technical term available chlorine available chlorine okay okay see pay attention I'm writing here the amount of chlorine liberated is called available chlorine available chlorine okay as the bleaching powder action bleaching action depend depends on the available chlorine content available chlorine content the greater chlorine greater available chlorine is is give you the better quality right so greater chlorine amount better is the is the quality okay hence higher the price obviously right in India all these are good quality product is available in higher price right higher the price okay leave it so a good sample a good sample of bleaching powder should contain how much of the chlorine ah yes Surya that is also true okay yes yes good quality actually yes better is the quality so a good sample a good sample good sample contains a good sample of bleaching powder actually it contains 35 to 38 percent of chlorine oops 35 to 38 percent of chlorine okay or I should say available chlorine okay next yes the uses uses you know very well it's very common used in textile industry for the bleaching purpose of the clothes and then in the laundry we use we use this as a disinfectants okay so there are so many uses of bleaching powder okay bleaching powder is good a good kind of oxidizing agent as well oxidizing agent okay yeah okay next next we have um yes baking soda my favorite I love this okay so common name of baking is what sodium hydrogen carbonate very well known correct and a preparation how can we prepare it you know what NaCl with water the concentrated NaCl solution is known as brand solution correct and if you have ammonia also in that then this is known as what ammonical brand solution ammonical brand solution correct yeah so when carbon dioxide gas is passed CO2 is passed through through ammonical brand solution ammonical brine solution it produces sodium bicarbonate and ammonium chloride okay sodium bicarbonate and ammonium chloride so sodium chloride plus water is the brine solution plus ammonia it is ammonical brine solution and when you pass carbon dioxide through this ammonical solution it gives you sodium bicarbonate sodium hydrogen carbonate and ammonium chloride okay ammonium chloride now on heating what happens on heating of this sodium bicarbonate it converts into sodium carbonate sodium carbonate sodium carbonate is again very important for us okay right we're going to learn about it right now on heating sodium bicarbonate produces sodium carbonate water and carbon dioxide so this carbon dioxide produces or this carbon dioxide causes the fluffiness in cakes pastries okay in cookies in doughs right that's why we add soda in pakodas in cakes in pastries and so many things okay because of because it released CO2 and we use sodium bicarbonate as in fire extinguisher as well if i remember it right am i right am i right aryan am i right akshita who all are available shavita use sodium bicarbonate as in fire extinguishing right okay so shavita you are here it it shows me your presence okay next yes so we use in household purpose obviously in household like ingredients yes ingredient of anti-acid okay making a baking powder what is the content of baking powder what is the content of baking powder baking soda plus acid but which acid it is tartaric acid baking powder is mixture of what mixture of baking soda mild acid and acid which is known as tartaric acid okay guys i have seen a question in past year the question list that what is the use of tartaric acid in baking powder and why do we prefer to add baking powder instead of baking soda any guess sucharita karthik sucharita hi first time i first time i saw your message here beta yes yes surya correct why do we prefer to use baking soda over sodium bicarbonate because tartaric acid tartaric acid controls a bitter test of sodium carbonate okay sodium carbonate first thing and it produces a good amount of presence of acid produces a good amount of carbon dioxide yes very good aryan correct it neutralizes the sodium carbonate very good good dish disha ananya very good content next one more thing let me just think what i was yes what is the name of the process by which we prepare this baking soda the process name is solvay process okay solvay process this process what we are following here okay this is known as solvay process or you can say ammonia soda process or monia soda process okay solvay process or ammonia soda process no no no aryan no no no this is the solvay process when you pass ammonical brine solution from carbon dioxide this is the solvay process okay and chloralkali process when you pass electricity from brine solution you all please hold as sharda mar will be joining in sometime hello everyone hope i'm audible now okay okay uh yes actually some power fluctuation happened so i'll share my screen again one minute one second tavishi tavishi beta you are the host can you please make me the host tavishi can you hear me are you there uh this is another problem tavishi yeah thank you okay thank you okay let's continue now i can share my screen so yes we were talking about uh water oh sorry washing soda we were talking about actually sodium bicarbonate and now let's talk about washing soda washing soda is what washing soda is just sodium carbonate with 10 water molecule attached in it right with water of crystallization yeah okay no problem tavishi thank you okay so uh yes preparation how will we prepare washing soda uh with by recrystallization of sodium carbonate by recrystallization of sodium carbonate okay or uh this 10 water molecule what do we say this this is known as water of crystallization okay right now uses we use in the glass soap paper industry okay we use uh we use to prepare in soda glasses actually we use in the cleaning agent in the domestic purpose removal of the hardness of water that's again very important use of washing soda right yes we use that in the manufacturing of borax okay sodium borate or boric acid borax okay yeah you know uh Na2 CO3 this is sodium bicarbonate and this is also known as soda ash soda ash and what is the common name of koH caustic potash okay caustic potash right so don't forget these common names right okay next what how can it react with the hard water how can it remove the hardness of water you know the hardness of water is due to hardness of water is due to the presence of what due to the presence of calcium and magnesium salt calcium and magnesium salt wait i'm not able to see your messages calcium and magnesium carbonate salts basically salt so on adding on adding Na2 Na2 CO3 what happens they are precipitated as a calcium and magnesium carbonate salts adding CaCO3 adding NaNO3 they precipitated into CaCO3 and MgCO3 which is insoluble in water and we can separate it correct and we can remove the permanent hardness of water right we can remove the permanent hardness of water okay now how will you take the softening of water if your water has softener now it's become softer now then it will start forming leather with water leather with soap okay hard water doesn't form leather with soap okay next next we have water of crystallization what does it mean by water of crystallization the fixed number of water molecule present in the one formula unit of a salt that is known as water of crystallization okay for example on heating copper sulphate water droplets appear the formula of hydrated copper sulphate is what CuSO4.5H2O so when we heat it this water will remove okay this water will remove usually it is blue in color blue in color so when you heat it what happens it converts into white white in color why because it converts into CuSO4 which is white in color okay next what is the example of water of crystallization formula in salt Gypsum CuSO4.2H2O CuSO4.2H2O right on heating Gypsum at 100 degrees Celsius or at 373 Kelvin it becomes CuSO4.5H2O which is the formula of plaster of Paris right which is the formula of what plaster of Paris now you know that plaster of Paris is used in the like plastering the fractures bone fracture bone correct so when plaster of Paris is mixed with some water it forms gypsum or when you leave plaster of Paris in the environment it becomes hard why because it reacts with atmospheric moisture and it converts into gypsum right so CuSO4.5H2O in POP in POP you have a half water molecule okay okay you have half water molecule in just one formula one formula of POP okay so when it reacts with one and a half water molecule not actually one and a half when it reacts with half sorry one and a half water molecule it forms CuSO4.2H2O which is the formula of gypsum right gypsum okay user plaster of Paris is what making toys decorative materials smoothen the surfaces right okay now we are going to start some doing some questions okay so next question we have the blue color of crystal of the substance changes changed on heating in a closed test tube but the color was regained after sometimes on cooling it so can you just tell me what is this blue color of material which material do we have very good so now not only CuSO4 guys please don't send me half of answers yeah Surya there are now questions and only questions remaining so we'll do just few questions and after that we will be doing a passage related question okay there are so many questions so if you want I can pose this presentation and learn is the question presentation okay don't worry the chapter division is got over only few questions are there so that you can do by your own as well okay don't worry yes the blue color salt name is what CuSO4.5H2O okay what is the reaction the CuSO4.2H2O when it gets heated it converts into what it converts into CuSO4 plus 5H2O and on cooling it on cooling it reacts with atmospheric oxygen atmospheric moisture and it again gains it again gains the blue color so this is what CuSO4 dot sorry dot 5H2O dot 5H2O okay so we have to name the substance and write the chemical formula what is the name of the substance copper sulphate okay name of the substance is what copper sulphate crystal crystal and formula you know this one this you have to write in bracket correct which turns from blue to white which turn from blue to white okay and again which turn from white to blue after exposure into moisture that okay next write the name and chemical formula of two such compounds whose one formula you need associated with 10 and two water molecule 10 and two water molecule okay tell me any any crystal any form of the crystal in which you have 10 and two water molecule quickly example the first example you can give me washing soda Na2CO3 dot 10H2O then another example you can give me gypsum right CaSO4 dot 2H2O correct and you have to write their chemical name sodium carbonate sodium carbonate dihydrate sorry decahydrate sodium carbonate sodium carbonate decahydrate decahydrate and calcium sulphate dihydrate calcium sulphate dihydrate okay decahydrate and dihydrate you have to mention okay next a student was given with the four sample of water in the four different test tube these were distilled water lemon water and water having diluted here okay fine water having any which also which sample which sample pH value will be more than seven will be seven sorry which sample value will be seven B yes correct answer good right good next if the pH of the solution changes from 3 to 4 the solution becomes very good let's I'll say like next the name of the scientist who proposed the acid base theory very good a Arrhenius has proposed acid base theory now please see here the theories are not there in your ncrt portion but the question was there in 2016 paper okay so always you need to learn little extra little extra that is not bad okay next name of the gas evolved in zinc metal react with HCL very good D correct what is the important property of the of an anti-acid of an acid sorry not anti-acid of an acid it's sour in taste correct good very good next when a drop of unknown solution X once again when a drop of unknown solution X is placed on the strip of pH paper a deep blue color is produced the solution be very good guys and it's correct on diluting an acid advice to add acid to water do not add water to acid explain why you can explain me you can tell me in short very good okay the on diluting an acid advice to add acid to water not water to acid why because it is highly exothermic process I'm writing in short because we do not have that much of time I'm writing this is the important and keywords okay you have to include this keyword in your sentences because it is highly exothermic process process okay when water is added to acid due to the small amount of water the heat is evolved okay we'll change it into the vapor right so acid will spill out and acid will spill out okay and may cause injury and may cause injury so it is advisable to mix acid into water not water into acid okay done understood see these are the keywords you have to include exothermic acid will spill out it may cause injury these you have to include in your answers okay next a student adds a spoon full of powdered sodium powder powdered sodium hydrogen carbon in the flask containing ethanoic acid okay list any two main observations okay so the two observation the first observation I'm writing is gives brisk effervescence it gives brisk effervescence okay with a colorless and orderless gas with a colorless orderless gas okay second observation you have to write two observations good actually both the observation I have written in the first point only the gas would be colorless and orderless it produces a gas which is colorless and orderless and it gives a brisk brisk effervescence okay okay so this is the answer for this one but you have to write a chemical equation CH3 COOH plus NAH CO3 gives CH3 COO NA plus H2O plus CO2 okay this is the equation okay guys I wanted to know one thing I wanted to know one thing from you the next chapter we are going to start metals and non-metals and what would you prefer just revising past year questions or theory and past year questions both the revision you want like how we have done in acid basis if you can hear me please answer what Ananya is saying past year questions I need the opinion of everyone in this okay okay so I have got 50-50% okay okay okay then thank you for all of your opinions yes so guys we will be doing both actually first theory and then past year questions okay so from the next time now I will not write answers here okay I will just write answer like maybe in my notebook or somewhere and I'll just upload the photo that will be more time saving for all of you right okay okay push me okay fine thank you beta okay next the white powder is an active ingredient of antacid that you know you can we can leave it let the equation show effect of heat on this this someone okay ah you know this question I know leave it okay let's do that thesis type of question which is here no here a solid compound x on heating gives carbon dioxide and a solid residue the residue when mixed with water it forms y on passing of excess of carbon dioxide through y water is clear solution and z is obtained so you have to tell me what is x y and z no no no the first one what is identifier x what is x but it can't be n a co3 yes yes are you now it is correct see a co3 and why why why why is no no no no think once again see the first one is calcium carbonate second one is your calcium hydroxide okay one second guys yes correct yes correct okay and then the last one is that is what that is what that is this one can see a co3 isn't it because this is soluble in water right so many of you have answered me for first and second what about the third one yes this is the a okay this is soluble in water so third answer z is what ca 8 co3 twice okay when you pass excess of carbon dioxide from the calcium hydroxide net converts into calcium bicarbonate okay next assertion and reason uh assertion and reason may okay because here you have option option a both the assertion and reason are true and the reason is the correct explanation okay d is what both assertion and reason are true but the reason is not the correct explanation okay and in c assertion is true but reason it falls and in d both assertion reason are false so now just check phenolphthalein is an acid an acid base indicator the phenolphthalein gives different color in acid you can basic medium you know it's a beta a correct right the answer for this is a assertion and reason both are correct and the reason is the correct explanation of assertion okay second ph of the ammonium nitrate solution is is acidic ph of ammonium nitrate solution is acidic the solution of salt is a weak base and strong acid what what should we answer for this so for second again eight okay ph of ammonium nitrate solution is acidic right is it what's happening so many messages d phenolphthalein is an acid base indicator right they just have to acid base indicator if it is colorless then it is acidic and if it is a pink in color it is a base so it is acid base indicator you have to be very specific with the words right relf for you are saying answer c for the third one really no for third one it is d i guess so ph of ph seven signifies not only signifies pure water ph seven signifies neutral solution okay that's why assertion itself is false and ph of acidic so acidic acid is greater than seven no it is less than seven so it is d okay and for second one it is a solution of ammonium nitrate is the acidic why because it is the combination of weak base ammonium hydroxide and strong acid that is nitric acid correct right okay got it everyone understood all the assertion and reason no no no shadow we actually see ph seven doesn't signifies pure water only okay it signifies the neutral solution it doesn't matter that ph seven if you have that will always be water no that will be neutral solution if you have a pure water that means pure water is a neutral solution that's why this assertion is false okay yeah okay guys so now we are done with these questions i will uh write all the answers of these questions and upload in the larnest all these questions how many questions are left i guess five questions are left okay and in the next class we will be doing metals and non-metals theory in one hour and then next one hour questions fine okay how was the lecture guys did you enjoy did you understand everything acid and basis was the biggest chapter yeah yeah it was too big okay okay guys good shallow engine who was there ma'am i'm shawani shawani beta i'll talk to you later you can send me message in whatsapp okay ma'am in your personal contact yes you have that okay ma'am thank you very much for the lecture okay everyone chalo bye guys bye take care enjoy bye bye welcome bacha bye welcome beta bye bye bye bye guys yeah thank you bye bye