Class 9 Science Chapter 5 | Solutions: Mixtures, Concentration & Solubility | NCERT Exploration

[00:00:00]Hello students, have you ever wondered how you start your day [music]?

[00:00:05]You drink milk, tea, coffee, juice and also eat some food. Right?

[00:00:11]So if I were to talk about just one thing [music], like, it's tea. Now have you ever wondered what ingredients tea is made of?

[00:00:18]You always drink it and what would you feel if you saw it? This is the same thing. But many things are mixed in it and only then tea is made.

[00:00:27]And that's how we feel, but it [music] is the same thing. And there are so many things that we mix [music] together but it still doesn't mix. Like if I put sand in the water or if I put pieces of wood in the water [music] how would it feel? No matter how much I mix them, they will still look different.

[00:00:47]Right? So what are all these things?

[00:00:49]We mix different things. Many look exactly the same. Many appear completely different. How do we separate them? Yes. This idea is how do we separate them? This idea is not just limited to [music] in your home.

[00:01:04]This idea has been used in big labs, in hospitals, when we test [music] blood samples, and many other things. [Music] Yeah, this is the science, the science behind it, what's the idea? What are the principals? Using these, such huge evidences are given in big forensic labs.

[00:01:23]Hey, what is all this? What are the principles?

[00:01:28]How do different things come together? And how can we differentiate them? Are there different techniques? That's all we're going to read in this [music] chapter. And we are going to read it in a very interesting way.

[00:01:39]And the most important thing [in music] is there is no order. We have to understand it so that we can know how science is connected to our daily life. So let's start. Let's start this chapter. Let's get started.

[00:01:56]So, let's start exploring mixtures and their separations. So what do you like to drink first in the summer?

[00:02:04]Sugarcane juice. Right? So what do we get from sugarcane juice, sugar cane sugarcane? Sugar is also available. So the sugar you use at home comes from sugarcane.

[00:02:15]And where does that sugarcane come from?

[00:02:17]Comes from the plant. Ok? That is a plant. Does it happen like this? There is sugar in it. But if we talk about doctors, they take drops of your blood and after detecting it, they tell you whether you have malaria, typhoid, dengue, what is the problem.

[00:02:35]Ok? So malaria can also be detected by using just a few drops of blood. Let's test it. That means something or the other is mixed inside them.

[00:02:46]With which we take it out and check it. That means it is mixed. What will we call this? Mixtures will speak. Ok? Now separating the mixtures means that a lot of things would have been mixed. Now what are the methods to separate them? There are different ones. Ok? Like if there is sugar in water. Sugar and water are mixed but the method of separating them will be different.

[00:03:11]Ok? So in this chapter we will understand this in depth. We will read about different properties. We will read about the behavior of different mixtures and different techniques to separate them. So first of all, to separate, it is very important for us to know about mixtures. So first of all how can we classify mixtures?

[00:03:37]How can I classify? There are many types of mixtures. So what are the different types of mixers? So on the basis of their composition? Composition means that on the basis of what it is made of, we can classify it into two things. There are homogeneous mixtures and there are heterogeneous mixtures.

[00:03:56]What are homogenous? Which have uniform composition. Now this has become a very difficult name. What do you mean by uniform composition? Uniform composition means like there is water inside a glass and you have mixed sugar inside the water.

[00:04:12]Ok? Now you have mixed it.

[00:04:15]Mixed it well. Now mix it well.

[00:04:18]All the sugar has mixed in the water. Now if you drink water, how will you like it? It will taste sweet. But if you keep water in front.

[00:04:27]Can you tell by looking at it? Hey, this looks like sugar to us. Here we can see water. No, right? Why? Because you have mixed all the sugar. Now you will see only sweet water. Isn't it?

[00:04:39]So from top to bottom you will see the same mixture. It is not that there is less sugar here and more sugar there.

[00:04:49]This will not happen. Everything will be the same. So we call it uniform composition and we give another name to these homogeneous mixtures as solutions, about which we will discuss in more detail later. Ok? Now let's come to what are heterogeneous mixtures? Heterogeneous means those which have no uniform composition. Like an example has also been given here. Sand and water means if I put sand inside water then what will happen to the sand? Yours will sit here. The sand will settle here. So now if you look at this, you can tell that there is water on the surface. There is sand down below. Even if I turn it, it will rotate for once.

[00:05:31]But she will settle down again.

[00:05:33]Right? So now we are not all the same. At some places it is water and at other places it is sand particles. Right? So this composition is what we call heterogeneous. That is non-uniform. Non- uniform is not the same everywhere. Ok?

[00:05:51]What is another example of homogenous?

[00:05:54]Vinegar means acetic acid in water.

[00:05:57]What is vinegar? vinegar. Like in homes, if you go to the kitchen, you will see a bottle of vinegar lying there. We use them in pickles. It is sour and sour.

[00:06:07]Ok? So there is vinegar. What is that too? In a way, acetic acid is present in water. That is, such an acid which dissolves in water and the entire composition becomes the same.

[00:06:16]And what other example is there? Aerated drinks like soda i.e. CO2 in water. That is, when you drink soda water. Isn't it?

[00:06:23]What's inside it? There is some foam inside the water, right? Fumes come. What are those fumes made of? of CO2. Now it is completely under water.

[00:06:32]You have such fumes. Isn't it? So now we cannot tell by looking whether there is CO2 here or not. So what will the whole soda water be? A same uniform composition that is homogeneous mixture. Is it clear? Now this is where the question arises that if I put oil in water, will it be categorized as homogeneous or heterogeneous? Tell me. Yes.

[00:06:56]In heterogeneous. Why? Because if we put oil in water. We ourselves know that oil does not mix with water.

[00:07:03]He remains on top. So now you can tell by looking at it that there is water here and there is oil here. That means it did not get mixed. The uniform was not made. It is not made the same. So that means that it is non- uniform and will be categorized under heterogeneous mixtures. So we can understand it like this also. If you look carefully here, you will see that this is a homogeneous mixture, meaning all the water is uniform. Isn't it? If we add wash sugar to water, it looks the same.

[00:07:32]That is uniform composition. Same if I talk about here. This is heterogeneous mixture. That means it is not uniform. If you look, it is light on top and below you can see that all the sand that we have put has settled down. So we can tell here that there is water here. There are sand particles here. So this is non uniform composition. Is this clear? Ok? Similarly, now an activity comes to you.

[00:07:58]We will take three goats in the activity.

[00:08:01]Ok? As you can see, there is a glass i.e. a bucket in which we have poured water. Ok? So there was a first goat. Ok?

[00:08:10]We will take the second bucket and put chalk powder in it. Yes. You play in class, you make a whole lot of chalk, you make it into powder. Yes. We will put chalk powder inside it. And similarly, inside the third, we will add some drops of milk along with water. So now we have made these three goats. Ok?

[00:08:33]What has it become in a way? The mixtures are ready. Ok?

[00:08:37]We have already added salt into the water. Ok?

[00:08:39]Salt has been added to empty water. Then we have added chalk powder in water. Then in the third we have added milk in the water. Ok? We made the mixture.

[00:08:50]So what did we do here?

[00:08:53]Laser light. Here you can see whatever you play. Ok? We passed these laser lights through it.

[00:08:58]Now here we have given you a very good warning that you should never put these laser lights directly into your eyes. Or one should not look into the eyes. Do not put it directly into your eyes because what are there in your eyes too? There are lenses. Isn't it?

[00:09:13]So it can damage your eyes. You must have noticed. Many times you go to concerts, big ones where laser lights are shining, concerts are held or big parties are organised. Wherever there is a laser light, it is installed above the DJ. And if people make videos with their phones, then if light falls on the phone, it also gets damaged. The phone's camera gets damaged. That means that lens gets damaged. So laser light causes a lot of damage.

[00:09:42]Even if it is your phone's camera, it will damage your eyes.

[00:09:44]Yes. So you have to take this laser light with great caution and pass it through this.

[00:09:50]So if you pass through this, you will see that you cannot see anything from here, whereas here you can see a dot of laser light.

[00:09:59]Same, if we talk about chalk powder, then here you will be able to see it faintly and here you can see laser light. Ok? And then you saw here that here you have proper light, you have proper path visible here. Isn't it? What was in the top? The proper path was not visible. Only the color was coming.

[00:10:22]That color was spreading. Here your proper color and proper path are visible. That brother, your laser beam is coming out from here.

[00:10:33]What does all this mean? This mixture should be the same but this mixture is showing you different results with the beam, that is, there are different varieties in these mixtures also.

[00:10:49]Right? Also what did we do then? Filter this water through filter paper.

[00:10:54][nasal sound] I fluttered this one and got this one fluttered too. And then we noticed what was left where on the flat paper.

[00:11:01]You notice it yourself.

[00:11:04]When there is sugar or salt in water, nothing will appear on the filter paper because it would have dissolved. Similarly, if we talk about chalk powder, the chalk powder will appear white. Similarly, if we talk about milk, what will come in the filter paper in the milk.

[00:11:17]Right? So we observed all these things and then we came to a conclusion that different mixtures are categorized in different ways and the techniques to separate them are also completely different. So this is where our first category of solutions comes in. Ok? What are the solutions?

[00:11:41]So a mixture which we are calling a solution is a homogeneous mixture. Ok? As we told you earlier, we also call them homogeneous solutions.

[00:11:51]Why? Because what do they contain? In a way, there is uniform composition. Like sugar and water, salt and water. If we mix them, the entire water looks the same. Ok? So these types of mixtures are called homogeneous mixtures.

[00:12:07]And in these we also call them solutions. And we will know the solutions better. Now, like when you noticed the first goat, what was inside it? There was water and salt.

[00:12:22]So what happened? In a way, we would call it a solution, that it was a solution.

[00:12:27]Ok? What are the categories?

[00:12:29]We will read about them now. So the solution is made up of two things. A solute and a solvent. What is a solute? The substance which dissolves you.

[00:12:40]And what is a solvent? The substance that dissolves the solute, that is, which dissolves it within itself. Disolve means something that dissolves, it is something that dissolves.

[00:12:52]For example, if we talk here, if salt gets mixed in the water, the salt will dissolve in the water. So salt becomes your solute and solvent becomes your water. Generally, the solutions that are available are presented to you in less quantity.

[00:13:11]Solvents are present in greater quantities.

[00:13:14]Ok?

[00:13:17]Similarly, if we talk about sugar and water, sugar is mixed in water. That is also a solute and water is a solvent.

[00:13:27]So now a question arises from here. Suppose I mix one spoon of salt in a glass of water.

[00:13:32]Ok? So what is that to you? There is a solution. What will happen even if I mix two spoons of salt? The solution will remain the same. So what about proportions? Can we express these quantities? Yes.

[00:13:50]We can express these quantities. We call this the concentration of a solution. What do you say? Concentration of a solution.

[00:13:57]Like understand one thing. Suppose there are two goats here. Ok? There is water in this and water in this.

[00:14:05]I have put one spoon of salt inside it and I have put two spoons of salt inside it.

[00:14:10]Which one will taste saltier when you drink it? The one with B. So the concentration of solute i.e. salt is high inside it. Ok? So we call this concentration of a solution. Let us understand this in more detail. So let us discuss the concentration of a solution. So let us take a very good example of ORS. What is ORS? Like sometimes you get dehydrated i.e. lack of water or you start feeling like vomiting. Ok? Or you may get diarrhea. If any problem arises in this manner, what do we do?

[00:14:46]Take ORS. Ok?

[00:14:48]What is the full form of ORS? Oral rehydration solution. Ok? Now how is it made?

[00:14:57]Salt, sugar and water are mixed in it in a fixed amount i.e. a specified amount. Only then a proper ORS is made. For example, let me tell you.

[00:15:07]Suppose if you have to make 1 litre ORS then it will require six spoons of sugar and half spoon of salt. Ok? So let's assume this is your fixed concentration.

[00:15:20]If we make even a slight change in it.

[00:15:23]Suppose we reduce this, increase this or reduce this or increase this, then if there is any change in salt, sugar, water, then we will not consider it as ORS. Ok?

[00:15:41]Will not be ORS. That will not be considered your ORS.

[00:15:44]Ok? And whatever sugary drinks you drink at home or in the market, the normal sugary drinks that are sold are fine, they are not ORS.

[00:15:56]Ok? All of that is not ORS.

[00:15:58]ORS belongs only to you and your WHO.

[00:16:02]What is WHO? You get ORS from the World Health Organization, which is basically authorized by your government.

[00:16:10]That is a proper ORS. The rest of the ORS that normal private companies are releasing is also not your original one.

[00:16:17]Ok? He will take care of this thing. So what does that mean? If salt and sugar are added in a fixed amount in proper water, then we will call it Orest. So we call it concentration of a solution. If you want to drink tea, then you will add proper amount of sugar, leaves and milk to it. If there is even a slight up or down, you will not get your according test.

[00:16:40]Right? So who introduced Oras? Met a Scientist Dilip Mahalnabi An Indian Pediatrician. Ok? Pediatricians first developed and implemented the treatment for the dehydration caused by diseases such as diarrhea and cholera. So first of all we will talk about Dilip Mahalnabis. What is that Indian Peritrichian.

[00:17:06]What are peritricians? There are specialized doctors for small children or those who are adolescents or teenagers.

[00:17:13]Ok? So he developed it for the first time that whenever there is dehydration i.e. there is lack of water in you.

[00:17:24]Ok? And you get diseases like diarrhea, cholera. So how can we treat it? So he had formulated ORS that has revolutionized the rehydration therapy, it has saved millions of lives after the World Health Organization popularized it worldwide. So he had introduced ORS and its therapy was done in a very good way, it was known everywhere that yes brother, this has brought a very good revolution, that is, if you are facing any problem, take this ORS, in this way he had saved millions of lives and after that the World Health Organization popularized ORS. As I just told you, the final original ORS which is government authorized is your World Health Organization. So this is their formula. Ok? This is Dilip Mahalanabis' formula. Is it clear? So he got it checked and popularized it due to which many lives of many people were saved.

[00:18:30]And what example can we take of concentration? Another example is pesticides. Now see what pesticides are? They spray such medicines on their plants so that the insects and pests die. Ok? So a fixed amount of pesticides is mixed with a fixed amount of water. Then it is sprinkled in the fields, on the plants. If this fixed amount is not there, if the water becomes less or more, suppose there is more water, pesticide in it becomes less, then your insects will not die properly, our crops will get damaged, right, if there is more water, sorry, water becomes less, pesticide becomes more, medicine becomes more, water becomes less, then also there will be damage to the soil, crop, environment, so we need a proper fixed amount, fixed concentration of water and pesticide, only then it will work. Isn't it? And what could be the examples? And think of the example yourself. Like I gave you an example. Gave an example of T.

[00:19:37]If you are not able to make a proper tea then you will not enjoy it. Isn't it? It is said that parents say, hey, I want to drink tea at home. I don't enjoy the tea there. I do n't enjoy tea in pouches. Why?

[00:19:48]Because in homemade tea, as per our requirement, we add everything according to our concentration.

[00:19:52]Ok? So the right proportion is always essential when preparing a solution. Whenever creating a solution, the right proportion is always important.

[00:20:04]Ok? The amount of solute dissolved in a given amount of solvent and solution is termed as the concentration of the solution. This is a good idea. And you will note that the solute that is formed when we put it in a proper solvent, okay? So what do we call that? Concentration of solution.

[00:20:24]Like I just told you, put one spoon of salt in some water.

[00:20:29]Add two spoons of salt in a pot of water. So whose concentration is higher? The one with two spoons. Isn't it? So we will call it concentration of the solution. Now where else does this happen? Are present in medicines.

[00:20:40]Now when you take medicines, then every thing that is present in the medicines, the chemicals, are present in proper amount, if there is any variation then the medicines will not work well for you or will cause side effects.

[00:20:53]I just told you that in agriculture we are talking about pesticides. Ok?

[00:20:56]As I just mentioned, the food is done, you are also cooking the food. Even if the salt is reduced, it will not be enjoyable. Even if there is too much salt, it will not be eaten. Cosmetics done. The cosmetics that you apply like creams, sunscreens, body lotions, soaps, they should also have proper concentration. If the concentration fluctuates, side effects may occur and problems may arise. Again, even for a simple cup of tea, you need proper concentration.

[00:21:23]Whatever amount you put into the solution or solvent, we call it the concentration of the solute.

[00:21:30]And that is the variant for your solution. If it gets messed up, goes up or down, then your entire solution can get spoiled.

[00:21:39]You may get damaged. Many problems can arise. Ok? So this was all about concentration of a solution. Ok?

[00:21:47]Where do we use it in our daily lives? Now how do we express concentration? Now how will you express your concentration? Suppose you only have food.

[00:21:58]Ok? How much salt have you put in the water?

[00:22:01]How will you write it, how will you represent it? So, let us represent or let us express concentration. So, let's talk about how do we express concentration? How do we express concentration?

[00:22:17]We have different methods to express concentration. Ok?

[00:22:20]Look at some commercial package products.

[00:22:23]You will see many things behind it. Ok? There are many other things as we express which you will read in Higher Standards. But for now, if you pick up any random packet, even at home, if you look at the back of it, you will find many lists.

[00:22:40]Like if you see, normal is a juice packet. Ok? If you look at its back side, you will be able to notice all the things here. Look carefully, what do you see in it? Energy.

[00:22:54]Ok? How many grams is protein?

[00:22:56]Carbohydrates. How many grams of sugar have you given me? 28 20.8 Okay. Added Sugar 20.3g Total Fat 8g. So these are the grams given to you. Isn't it? Right? So what are all these things that happen?

[00:23:12]What do you understand about these?

[00:23:14]Ok? So that is what we are going to discuss now.

[00:23:16]An example of milk powder is also given in your book.

[00:23:20]Ok?

[00:23:22]How much fat is in it? How much sugar is there?

[00:23:25]How much fiber, protein, sodium is there? Ok? It is written here that it is 100 grams on average. That means for every 100 grams you will get 26 grams of fat and 49 grams of sugar. Ok?

[00:23:37]You will get 15.5 grams of protein and 0.8 grams of sodium. So how are all these things explained? Let Us Discuss. So the first method is, well here three main ways have been told to you.

[00:23:51]Well, there are many several ways which you will study in high standards. But basically three main ways have been expressed to you here. The first one is your mass by mass percentage. Ok? Or we also call it weight by weight percentage. How do they remove this? This is the mass of solute upon the mass of solution * 100. Tells how many grams of solute are present in 100 grams of the total solution. That means if you have picked up 100 grams of any solution, how much solute is there in it?

[00:24:22]How much sugar is there? How much fat is there? How much protein is there? Like we just told you here, how do we take it out? Mass of Solute What is the mass of solute? What is the mass of solution? Like, let's say something simple.

[00:24:35]We can understand this like this, suppose you have taken 190 grams of water inside a bucket. Ok? And you have added 10 grams of salt in it.

[00:24:51]Ok? Added 10 grams of salt. So, what is your solution? Mass of Salute What happened to you? 10 grams. And what happened to the mass of solution? Solution means what is the total mixture? 190 + 10 that is 200 grams. Ok? Now if I calculate the mass by mass percentage.

[00:25:14]So what is coming out? Mass of solute up to mass of solution * 100 cancels out. Here you go, 5%.

[00:25:25]What does it mean? This means that if you have drunk 100 grams of water out of this 200 grams, then how many grams of salt have gone inside you? 5 grams of salt has been added.

[00:25:40]Is this clear? So that is why whenever you have any packets etc., it is written on the back of it in particular quantity that you will get so many things in 100 grams.

[00:25:54]Proteins, salt, sugar, energy, all these things are written to you that in 100 grams you will get so much products, so much solutions. Ok? So this means that in 100 grams of water, you have 5 grams of salt. Ok? This method is used to express homogeneous and heterogeneous mixtures. Milk powders, spices, salt, sugar, protein present in them. That means, if you assume, as I just told you, that you have the entire solution. Ok?

[00:26:28]Suppose you had this solution inside this, you had 100 grams. Ok? Suppose there was 5 grams of salt inside it. There were 5 grams of sugar, 5 grams of protein. These were all the things. If you have to extract it, then assume that you have to extract only protein. Ok? So what will be the mass by mass percentage of protein?

[00:26:49]Tell me the total divided by 5. What is the total solution?

[00:26:52]100 is not the total. What is the total? 5 + 5 + 5 + 100 is 155 * by 100, so now you will know this. If we calculate, it will come out to be 5 * 2 5 * 3, so 100 / 23, whatever is calculated, that much gram of protein will be present in you in every 100 gram solution. Is this clear?

[00:27:18]Ok? Now let us take an example for this.

[00:27:20]So let's start with the example 5.5. If 10 grams of salt is dissolved in 90 grams. of water Calculate mass by mass percentage of the solution form. So let's say you have a goat that had 90 grams of water inside it.

[00:27:40]Now I added 10 grams of sugar into it.

[00:27:44]Added sugar. Added 10 grams.

[00:27:48]Ok? So 10 grams of sugar.

[00:27:53]Sorry, salt is salt. Ok? Here you have water. Ok? So how much total do you have now? So how much do you have 90 + 10? You have a total solution of 100 grams in a beaker.

[00:28:05]Ok? that'll be.

[00:28:08]So let's write it here. Now we know what the solution is made of?

[00:28:15]From Solute Plus Solvent. Isn't it? So what is a solute? What is being resolved here?

[00:28:20]Salt. And what is solvent? Water. So how much salt was there? 10 grams. How much water was there?

[00:28:27]90 grams So what is the total solution?

[00:28:29]100 grams. Ok? Did you understand? Now how will we write this? So look, we'll write down what is the mass of solute? And solute here is salt. How much is it? 10 grams.

[00:28:42]What is the mass of solution?

[00:28:45]Mass of solution. How will the solution be made?

[00:28:47]Made from salt plus water. Isn't it? So salt was 10 grams, water was 90, so the total became 100 grams. What do you want now? Mass by mass percentage. So what was its formula?

[00:29:01]Mass of solute upon mass of solution * 100 so this will become how much solute was there?

[00:29:12]10 The solution was 100 * 100 right? 100 to 100 cancel. This is 10 grams. What does it mean? What will you get in every 100 grams of solution? You will get 10 grams of salt. If it is 200 grams then it will be 20 grams, if it is 300 grams then it will be 30 grams. Did you understand? Is this clear? Ok? So these 100 grams, sorry 100 grams, this percentage is being calculated.

[00:29:39]So we are 100% sure that you have got the percentage of this. That means you will always get 10 grams of salt in 100 grams of solution.

[00:29:50]So how much will it be for 20 grams of solution, sorry, 200 grams of solution, 20 grams for 300 grams, 30 grams for 1000 grams? 100 grams.

[00:30:02]Is this thing clear? Ok? So this is your first method.

[00:30:08]Ok? The first method is to calculate your mass by mass percentage. What is the next method? The next method is now you have mass by volume percentage. That means you take the mass of solute and from here take the volume of solution. This method is used where measuring the volume of a liquid is easier than weighing it. For example in medicines and in laboratories. See what happens? Many times like we took Mass of earlier Mass of solute upon Mass of solution. Sometimes it becomes difficult for us to calculate and measure the solution. So we extract their volume in laboratories.

[00:30:47]What does volume mean? Whatever they are into. Isn't it? If you are lying in a goat then take the dimensions of the goat.

[00:30:54]Lying in a flask.

[00:30:56]Took the dimensions of the flask. So we apply that. Let's turn up the volume. That becomes easy for us. Isn't it? So a common example is 5% glucose solution. It tells how many grams of solute is present in 100 ml of solution. Now look, we're taking volume here. So for volume we will use ml. So, he has given a very good example of this that is 5% glucose solution. We all drink glucose. Ok? So how is 5% glucose solution made? It tells how many grams of solute is present in 100 grams of solution. That is, 5% 5% means that 5 grams of glucose is present in 100 ml.

[00:31:32]100 Every 100 ml contains 5 grams of glucose. Is this clear? Ok? Let us take another example. Will you understand it well?

[00:31:45]So what is Example 5.2 saying? If 5 grams of glucose is dissolved in water to make 100 ml of solution, calculate its concentration in mass by volume percentage. So obviously mass by volume will be the result.

[00:31:59]Why? Because here five is given in grams mass and ml means it is given in volume. So what is there here? Suppose you have 100 ml water inside it. Ok? 100 ml water is not enough to make 100 ml of solution. That means the total solution prepared is 100 ml.

[00:32:24]So it is very important to read this thing.

[00:32:26]What was there in the earlier examples? There was water.

[00:32:29]We had added salt to the water. Then we found a total solution. Here we have been told that only 100 ml solution will be formed if you add 5 grams of glucose in it.

[00:32:40]Ok? So here we will write mass of solute.

[00:32:45]And what solute do you have here?

[00:32:47]Glucose.

[00:32:49]How much have you given? 5 grams. Ok? And here the volume of solution is already given. Look here, you do n't need to do plus anymore. I have already given you the solution.

[00:33:00]How much?

[00:33:03]What will you extract from 100 ml? We will calculate the mass by volume percentage. So what happens? Mass of solute upon volume of solution * 100 then what is the mass of solute? 5 Volume of solution 100 ml * 100 So how much is this? 5% So 5% glucose solution has arrived. That means what will you get 5 grams of in every 100 ml? You will get glucose.

[00:33:37]You will get 5 grams of glucose in every 100 ml.

[00:33:39]This is what it means. Ok? Now similarly you get the third method, Volume by Volume Percentage. Ok? What will happen to Volume by Volume? Volume of solute. Volume of solution * 100. Ok? This method is used when two miscible liquids are mixed. What is meant by miscible liquids? The two that get mixed inside each other. Ok? The two liquids should mix together.

[00:34:05]Ok? Like perfumes, perfumes are not made from just one thing. Two liquids have been mixed. Two liquids are mixing.

[00:34:12]What were we doing till now?

[00:34:14]We were putting a solid inside a liquid. Were you adding salt or glucose or sol sugar?

[00:34:18]Now if we mix two liquids here, it will become volume by volume.

[00:34:23]We also mix liquids within cosmetics. What does vinegar contain? Acid is poured into water. Isn't it? So how much acid did you add, its volume, how much water did you take, its volume. Ok? It tells how many ml of solute is present in 100 ml of solution. That now the first Grams were being talked about.

[00:34:42]Now how much solute is there in ml here?

[00:34:44]Look, ml is used for liquid.

[00:34:47]Grams are used for our solids.

[00:34:49]Ok? So how much solute have you added in 100 ml solution.

[00:34:55]Ok?

[00:34:58]Note: Commonly used in industries is weight by weight Percentage as weight and the mass are generally used interchangeably numerically Both percentage mass by mass weight by weight are equal to each other So what do we use normally in industries? You can call it weight by weight or mass by mass because we are considering each other the same. Well, you will come to know later that there is a difference between weight and mass.

[00:35:22]But here we consider only how much weight is coming on your weighing machine.

[00:35:27]That is considered as a mass here.

[00:35:29]Ok? Is this clear?

[00:35:31]Good. Now as we also read volume by volume. We also read Mass by Volume.

[00:35:37]We also read Mass by Mass. Of the three, the one you will use the most and is the most accurate is the first one mass by mass. Why are we saying this? Because the volume can be changed by you.

[00:35:53]Ok? How can change happen?

[00:35:56]Suppose the atmosphere changes, the temperature changes. Ok? So what will happen? Or if you change the container, the volume may change. Is this clear? The volume may change. But if you talk about mass, your mass will remain fixed.

[00:36:16]Whatever its mass, it will remain fixed for you.

[00:36:19]Ok? So if you talk about any volume then your volume can change. So it does not have that much accuracy. Is this clear? Ok? So let's take an example of volume by volume.

[00:36:31]So what is Example 5.3 saying? If 1 ml of a liquid pesticide is mixed with a sufficient amount of water to form 100 ml of a pesticide spray for rice crop, calculate the volume by volume percentage. So what have we done here?

[00:36:48]We have added 1 ml of pesticides in water so that 100 ml of pesticide spray is made. That means how much should your total solution be? Makes 100 ml. That means they have mixed it and told you. That means there is 1 ml of pesticides and 99 ml of your water inside it. Then together you get 100 ml pesticide spray i.e. pesticide solution for your rice crops. Now you have to calculate the volume by volume percentage. So it is a simple thing. What will you write?

[00:37:22]What is the volume of solute given? What is the solute here? Pesticide. I have given 1 ml, okay, then what is the volume of solution, volume of solution is 100 ml, so what do you have to calculate, volume by volume percentage, okay, so what will you do, this is volume of solute up volume of solution * 100, so volume of solute is one solution is 100 * 100 cancelled out, what comes out? 1% means what does it mean? That 1 ml of pesticide will be found in every 100 ml of water.

[00:38:10]Ok? This is volume by volume percentage. Ok?

[00:38:17]That's where Threads of Crocity comes to you.

[00:38:20]That is, what else can you know about it that a saline dip in hospital is usefully 0.9% mass by volume i.e. sodium chloride common salt in water i.e. the drip that you people get in hospitals, saline drip, is used when someone gets dehydrated. Ok? It seems like a saline solution, so what is inside it? What does 0.9% mass by volume mean? That is 0.9 grams of salt is present in every 100 ml of solution. Every 100 ml of solution contains 0.9 grams of salt. Have you seen it? 0.9 grams of salt.

[00:39:05]What is sodium chloride? The common salt found in homes is your present. Ok? Inside 100 ml of solution.

[00:39:14]Ok? 0.9 Saline Solution Is Safe For The Blood And Replaces The Lost Fluid In The Body. It is safe to such a percentage that it is good for our body. Ok? So let's start with the very first question of pause and pounder. A common talcum powder contains 4% mass by mass zinc oxide which acts as an antiseptic. How much zinc oxide is present in 300 grams of talcum powder? So look what he has told us, look at the talcum powder which we use in normal homes.

[00:39:49]Ok? Many times we get rashes or redness, so we use powder.

[00:39:54]So that makes us feel that yes, there is relief.

[00:39:56]Why? Because it contains zinc oxide which acts as an antiseptic.

[00:40:00]Ok? So if we are told that you get 4% zinc oxide in talcum powder.

[00:40:06]Ok? The mass by mass percentage given to you is 4%. You have to tell how much zinc oxide will be there in 300 grams.

[00:40:16]Ok? So first of all we know the formula of mass by mass percentage. What happens?

[00:40:24]What is mass by mass percentage? Mass of solute mass of solution * 100 This is what we have. Ok? Now what have you been given here? Here you get mass by mass percentage already given as 4%.

[00:40:49]Ok? What do you want to remove? You have to find out how much zinc oxide is present? So I had told you earlier also that the solution consists of two things. One is solute and the other is solvent. Ok? So what is a solute? Which dissolves and what is the solvent, which dissolves within itself or it happens in laser quantity. This mostly happens in large quantities.

[00:41:17]What's inside zinc oxide talcum powder? It is a solute. So you have to find out how much zinc oxide i.e. the mass of solute.

[00:41:26]Ok? And you have got the complete solution of talcum powder, it is a complete solution, it is consist of many things, so the talcum powder that I have given you, 300 grams, what is this, it is a complete solution, this is the solution and this is your solute and the mass by mass percentage has been given to you, so what will we write in its place, it is 4% mass of solute, that is, mass of zinc oxide, you do not have to remove this.

[00:41:58]Ok? The mass of solution given to you is 300 grams * 100, right? 100 to 100 cancel three left.

[00:42:08]Cross multiply this and you get 12 grams. This is the mass of zinc oxide you were looking for. Is this clear?

[00:42:19]Ok? Ok? This is your answer. And by the way, if we talk about what is 4%? What does 4% mean? What does 4% mean?

[00:42:30]How much zinc oxide is there in 100 grams of your product? 4 grams of zinc oxide. This is what it means.

[00:42:38]Right? We read that mass by mass means 4 grams of zinc oxide is present in 100 grams of talcum powder. This was its meaning.

[00:42:58]Ok? So you can see for yourself that if the talcum powder has tripled then your zinc oxide has also tripled. It has increased three times. clear? So this was your first question. Let's ask the second question.

[00:43:09]So let's read the second question.

[00:43:11]What are you saying? Your mother gives you a bottle of orange juice. Concentrate to mix with water and serve it to your visiting friends. So your friends have come to your house and your mother gives you a bottle of orange juice.

[00:43:24]Basically you can apply it in one way. Apply Rasna.

[00:43:28]Gives a bottle of Rasna. Ok? He says add two tablespoons of it. Ok? of water so that a glass of tumlar is filled. That means you are putting two tablespoons in one glass.

[00:43:46]Whose?

[00:43:49]Of Rasna or orange juice. Ok? And then it fills your glass completely.

[00:43:55]And the glass is such that if each tablespoon measures 15 ml, then it means that 15 ml has been poured twice.

[00:44:02]So you have added 15 ml twice in the water so that the total amount of water you will get for one person, how much will this glass prepare for one person? 150 ml.

[00:44:15]Ok? This will make a total of 150 ml. Now you have to find out what is the percentage volume by volume of the orange juice concentrate in the mixture you prepared. So you have to calculate the percentage volume by volume. Ok? So it is a simple thing.

[00:44:30]We have studied the formula of volume by volume.

[00:44:32]What happens?

[00:44:37]What is the formula for volume by volume percentage? Volume of solute upon volume of solution * 100 ok? Now what is the solute here?

[00:44:50]You have orange juice, it was poured twice and there is 15 ml in the spoon and it was poured twice, so what is the total? It's 30 ml, right? So what is the volume of solute? 15 + 15, this is your 30 ml. Now many children might be thinking that ma'am how will we know? Even if this volume by volume was not asked, only percentage was asked, we would still have calculated the volume by volume.

[00:45:16]Why? Because you can see their SI units. If given to you in grams.

[00:45:22]Ok? And your solution is in grams. So gram is gram, so month by month will come out. ml. ml is always yours in what? There is volume.

[00:45:33]Ok? There is volume. Liters always come in volume. So if yours is given in this manner then what should you do?

[00:45:40]Volume by Volume. That means your solute is also in ml. And if your solution is also in ml then volume by volume. And similarly, if here the quantity is given to you in grams and here the solution is given to you in litres or milliliters, then what will you do? So mass by volume will be applied. Is this clear? Ok? So you must check their SI units and calculate them according to what is asked.

[00:46:04]Ok? So the volume of solute is done. Now what is your volume of solution? So how much will the total glass cost to make? 150 ml, so put the values here. So 30 / 150 * 100 minus one zero cancels out 5 * 2 plus 5 * 3 plus 10.

[00:46:25]You have got 20%, so what does 20% mean? What does it mean how many ml of your orange juice was in 1 ml?

[00:46:40]20 20 ml was your orange juice but in 100 ml.

[00:46:45]Ok? This is what it means. Ok?

[00:46:48]So, this was your question number two.

[00:46:50]Let's do question number three.

[00:46:52]What is question number three saying?

[00:46:54]Vinegar used as a few preservatives and additives contains 5% volume by volume acetic acid. Glacial Acid S Glacial Acetic Acid Is A Liquid That Is 100% Acetic Acid. If you want to make vinegar from glacial acetic acid, how would you proceed? So look, it's a simple matter here.

[00:47:16]You are not asked anything numerical here.

[00:47:18]You have been asked a question, told about it, explained about vinegar, which we use as a food preservative in our homes.

[00:47:26]What does food preservative mean? Like when it is put in pickle, it becomes sour, when it is put in pickle, our pickle gets burnt for years. Isn't it?

[00:47:35]Why is it called a contain additive? Additive means it brings sourness. Anything is being added.

[00:47:39]Ok? So it brings sourness. Contains 5% volume by volume acetic acid. Ok? What this means is that 5% of it is acetic acid. This means how is vinegar made?

[00:47:54]Vinegar is made up of 5% of your acetic acid.

[00:48:00]From acetic acid. What does it mean? This means that your 5% i.e. 5 grams of acetic acid is present sorry it is volume by volume so we will not write grams, we will write ml. So 5 ml of acetic acid is present in 100 ml of water.

[00:48:27]Water or 100 ml of solution.

[00:48:30]What does solution mean? Water plus acetic acid. Acetic plus water. Ok? That means the solution is complete. This is what it means. Ok? Now Glacial Acidic Acid Is A Liquid That Is 100% Acidic Acid. Now what is glacial acidic acid?

[00:48:48]Which contains 100% acidic acid. That means there is no water inside it. It is all acid. If you want to make vinegar from glacial acidic acid, how would you proceed? If you want to make vinegar from glacial acidic acid, what will you do? How will you proceed? So it is a simple thing for you. Where will we mix 5 ml of acidic acid in? Where will you mix it?

[00:49:15]Not within 100 ml of water, but within 95.

[00:49:19]Why? Because if you take 100 ml of water and on top of that you mix 5 grams of that also.

[00:49:24]Or if you take 5 ml then the solution becomes 105. What do we have to do?

[00:49:29]We have to make 100 ml total solution.

[00:49:32]Ok? So what will we do?

[00:49:34]We will add 5 ml of acetic acid in 95 ml of water to make it 100 ml of solution. Now what will that solution be? At this time, your solution will be vinegar. Is this clear? Ok? So, this was your question number three. Next, now you come to a very important thing, that is solubility of substances. Till now we were talking that this will get mixed inside it, this will dissolve inside it, this will dissolve inside it. But what dissolves and what does not? When does it dissolve? What is the effect of temperature? And what happens on the solution? We will read all these things now.

[00:50:29]So we are going to study solubility of substance.

[00:50:32]The maximum amount of solute that dissolves in a fixed quantity of the solvent 100 ml and 100 g is called its solubility at a given temperature.

[00:50:46]What does it mean? This means at any given temperature, suppose I am sitting at room temperature. What does room temperature mean? Wherever you are sitting at this time, whatever room you are sitting in, okay? Normal temperature around there.

[00:51:00]Ok? What have you done inside it? So, suppose you have taken a fixed amount of water here.

[00:51:09]Ok? Let's say take water or you can take any solvent.

[00:51:14]Your alcohol may also come in the solvent. Any other solvent kerosene oil everything can be a lot of things. But to make it easy for us, we assume what is inside it? There is water. Ok? There is water inside it and you are sitting inside a simple room.

[00:51:29]You put a spoon of salt inside it.

[00:51:33]Ok? He dissolved. Ok? If it dissolves then we will say that it has become soluble in it.

[00:51:41]Ok? Ok. Then we will add one more spoon of salt inside it. Then that too will dissolve completely. Without being seen anywhere.

[00:51:50]Ok. Then we will add the third spoon.

[00:51:54]So now what will we feel that brother, it is not opening now.

[00:51:57]Some of it has opened up but some particles are settling down below it.

[00:52:01]And we are trying to mix it as much as we want. I ca n't mix it anymore. So now that most of it has dissolved inside it and is not able to mix. Now what will we do with it separately? We will filter it. We will do it. We will separate these particles. This means that now you have such water prepared in which no more salt can be added. Ok? So, if the maximum amount of solute has dissolved, then what do we call it?

[00:52:32]Solubility speaks. And when this solution cannot hold any more absolute solute at this temperature, we call it a saturated solution. So a solution that cannot dissolve any more solute at that temperature is called a saturated solution.

[00:52:53]We will call this a saturated solution. When no more salt will dissolve in it. And another simple thing is that if I had put a spoon inside this. Ok?

[00:53:04]One spoon of salt would have been added to this water.

[00:53:07]Now you can add more, right? But I did not put it. That means it is incomplete right now. Isn't it? It can be dissolved further inside it but I did not dissolve it. So we call this unsaturated solution.

[00:53:19]Ok? And the solute can dissolve and we have not molded it. That is unsaturated. I ca n't dissolve any further. It has dissolved completely as much as it could.

[00:53:28]That is saturated solution. Ok? Now if I say, now if I say, but I have to mix it further into it. So what should I do? So I will get up from my room and put this water on the gas. Now that the solution is heated, I can add more salt to it. Yes, solubility increases with temperature. So the hotter it gets, the more salt I can mix into it. Ok? So this is the point that the solubility increases as the temperature increases. But who is this for? It is for liquids. But let's say it's about gases, okay? If anything is soluble in gases, then its solubility decreases if we increase the temperature, that is, at low temperatures the gases dissolve more things in themselves, but if the temperature increases, then the dissolving capacity, solubility, dissolving power of the gases decreases with the temperature. Is this clear? Now we will understand this solubility better. We will read its graph. He studies. So now let us understand its graph.

[00:54:54]This graph shows you the solubility curves of compounds A and B in water. That means you put two compounds in water.

[00:55:02]Ok? And what did you do to him? Check how they meet.

[00:55:09]Suppose this is water. Ok?

[00:55:12]A compound has been added here inside the water. This is water and inside the water you have added B compound.

[00:55:18]Compound means, let's say this has become sugar.

[00:55:20]This has become salt. You can understand in this way.

[00:55:22]Right? Or it became glucose. It got salty here.

[00:55:26]You can understand it in this way also. You can believe anything.

[00:55:28]Any compound is. Ok? Now [nasal sound] what have we done here? We have calculated the solubility in grams per 100 grams of water, that is, how many grams of water are dissolving in 100 grams of water, along with the temperature.

[00:55:48]Ok? So we made this graph and this graph of solubility versus temperature, this curve is called solubility curve.

[00:55:57]From this we come to know, by reading we come to know how much it is going to dissolve in water. How soluble is it in water? Ok? Let's read this once.

[00:56:07]Speaking of Compound A, what happened? That was its solubility at 10°. It was this much at 20. So at 30 degrees Celsius it is 40, at 50, 60, 70, 80, so you will notice from here that the solubility is increasing with temperature. Even if A is increasing in small amounts in the compound, it is increasing.

[00:56:30]Talking about B compound, the solubility of B compound is increasing very well. If we look at B compound, it was this much at 10.

[00:56:40]Then it increased by another 20. It increased a lot at 30, 40, 50, 60, 70 and 80.

[00:56:45]So compound B is more soluble in water as per temperature as compared to A. Solubility of A is less. B is more in quantity as compared to A but both are soluble and both are increasing with temperature. Isn't it? The solubility of both is increasing with temperature. We understood this.

[00:57:07]Now there are some statements based on this information.

[00:57:09]We read them. The first statement is the solubility of compound A in water at 20°C is less, more, or the same at 60°C. Ok? So talking about the solubility of A compound, this solubility in the solubility of A is coming here and is here at 60.

[00:57:32]So the solubility is low at 20, right? It is more at 60. Ok? So the solubility of compound A at 20°C is less than that, right? It is less at 20° and more at 60°.

[00:57:48]Suppose we did not have the graph, we still know that solubility increases with temperature. So if this temperature is low then it will be less. At 60° the solubility will be higher. Similarly, if we talk about B, then at 20° it is less or more than 260. Even if I do not see the graph, I know that it will be less.

[00:58:09]Why? Because if the temperature is low then the solubility is low and if the temperature is high then the solubility is high because we are talking about liquids.

[00:58:15]Right? Speaking of liquids. I just told you that when it comes to gases, solubility decreases with temperature.

[00:58:22]But the solubility of liquids increases with temperature. So now let's look at the graph also. If you look at B, this is at 20 and this is at 60. So that means it is this much.

[00:58:35]Ok? So it decreased at 20 and increased at 60.

[00:58:38]So what do we write down what's on 20? Less than its solubility as 60°. Ok?

[00:58:47]What did you ask him last? The solubility of dash increases more than dash of with an increase in the temperature. They are saying whose solubility is increasing with temperature? So if we look at the graph, we can see that the solubility of A is increasing slowly. I mean, look, it has been around 50, right? Accept this, it was less. It has been around 40 to 60.

[00:59:18]Right? But if you look here, its solubility has increased from here to here. That means the solubility of compound B increases more with temperature as compared to compound A. So we'll write so come the solubility of B increases more than that of A with an increase in temperature. Is this clear?

[00:59:43]Ok? Next, we're asking what do you think will happen if you make a saturated solution at a higher temperature and cool it down slowly. What will happen? If you remember a saturated solution, what was a saturated solution? That when no more solute can dissolve in that water.

[01:00:02]Ok? You dissolved as much salt as you wanted in water but it is not dissolving or you dissolved sugar as you wanted but it is not dissolving. That saturated solution is ready. You have prepared it at a higher temperature.

[01:00:13]That means now you can boil it as much as you want. Even after that, it is not dissolving. And after mixing it, you have now cooled it down. What will happen now?

[01:00:26]What will happen? So what will it be? We will study that in the next lecture and in the next lecture itself we will come to you about different methods of separation if you have mixed a mixture.

[01:00:35]Now how will you separate it? We will study different methods. So thank you. That's all for this video. Stay tuned for the next [music] lecture.