Transcription
Hello everyone, welcome back to our YouTube channel. Today, I'm gonna show you P5 science. Okay, what are the concepts and what are the key words that you need to know for this topic? Let's take a look.
Okay, remember, I love learning. We teach science in a very precise, very concise way so that you know exactly what are the key words needed in order to answer the questions that you are asking your test paper.
Okay, so what are the key words that you need? The state of water depends on its surrounding temperature. So, what state of water will will depend on how cold or how hot the surrounding is. So, in order to be solid, even it to be very, very cool. Okay, so the particles are basically all lumped up together. They don't really have energy to move. So you can imagine like they're human beings, they're very, very cool, they're all lumped up together, so they are solid.
Okay, so what is the melting temperature? In order for them to move around, to start moving, to have energy, imagine human beings again. You want to start moving instead of shivering over there, you need some energy, needs some warm front. So, this will be the melting point whereby they move and then start taking the shape of the container, their liquid.
Okay, so they gain heat from the surrounding. The melting point is always zero. Even when they are ice, they are melting at a site of water might be a higher temperature, but the ice, even if it's melting itself, it is still at zero degrees Celsius.
Okay, impurities like saltwater can lower the melting point of ice. Therefore, there will be some test questions that assess you why is it that we make ice cream, for example? You need to add ice to the salt, add salt to the ice. Okay, it's up to the ice to decrease the temperature of the ice so that you can actually freeze up the milk that you had to make the ice cream.
Okay, so these are just common questions. You will see some questions later. We'll teach you. So, liquid, how does it look like? Liquid will be they take the shape of the container. They have energy, they're moving already. Okay, so they are not as packed as ice anymore. So, they are boiling point is a hundred degrees Celsius. 100 degrees Celsius meaning they gather a lot, a lot of energy to overcome their water state and fly out to evaporate.
Okay, so the temperature of boiling water remains at 100 degrees Celsius until all the water has boiled. So, you'll be 100, 100, 100, and they go up. They rise up, right? So, rise up as steam, rise up as water vapor. Impurities here increase the boiling point of water, meaning the dirtier the water or the more chemicals that you add on to the water, you would take a higher temperature for it to boil.
Okay, yes. So, how do I guess? We'll guess take the condition of the container as in definition, independent volumes, or you will just whatever is the container that I guess it's just all around. So, when does water take the state of gas? Your water vapor or even steam. But remember, a lot of children thought what they see there's plumbing out of the the boiling kettle is actually steam. No, whatever you can see, water droplets. Steam and water vapor cannot be seen.
Okay, so why are they? What the droplets that you see? Because the steam is so hot. The moment it comes out, the surrounding is colder. The moment the steam touches the cool surface of the surrounding, it condenses into what? The droplets. That is why you can see them.
Okay, so remember that steam and water vapor cannot be seen. What you see vomiting out from the kettle is actually water droplets already. They are condensed.
Okay, so this is a common misconception that children have. What are the other processes I need to know for this topic? You need to know this process called condensation. Children, a lot of times they can't spell this right. So, please cut this up so that you can know how to spell this. It's corn, C-O-N, D-A-N, D-E-N, S-A-T-I-O-N, tion. Cut it up so that is easier for yourself to spell it right.
Okay, so condensation is actually a state of becoming from yes, your state, no moving around, a lot of energy, and then you slowly you lose heat and then you become what? So, how do you lose it? So, you imagine. So, when water is evaporated, a gas is thick, right? They have a lot of energy. But the moment it touches a cool surface or they lose energy and they become slower in movement, so they become liquid.
Okay, so you imagine these particles as little human beings. You're cool, you move a little bit less. Okay, so it can, okay, any temperature. Basically, if the water vapor just a cooler surface, it will lose energy and condense. So, it's basically any temperature that is a bit cooler. So, you know, in preparation, will be home, liquid.
Okay, so yeah, yeah, yeah, yeah, moving around with a little bit of energy. But you evaporate because you gain energy and you go, wow, you have energy, you feel like yes. Okay, so you become the water vapor state. You have a lot of energy. So, that in preparation is gaining heat. You'll be surprised. In a water question, there is a lot of new section for heat keyword. So, condensation is lose heat. Evaporation is gain heat.
Okay, heat in this case is actually referred to as a form of energy for the water. Okay, so again, you can occur any temperature. Again, it's from the surrounding. So, even if you just have a pool, a pour water on the floor, it will evaporate because the surrounding, the game heat from the sun, only begin the energy from the surrounding. So, the hotter it is, the more water they, the more energy they gain, the faster the rate of evaporation. We shall touch on later.
Okay, so the rate of evaporation is affected by four factors. You need to memorize all these four. Sometimes the exam questions are only asked for three. Some schools only teach three, but that's actually four altogether. So, it is good information for you to know them.
So, one is the area of exposed surface area. Okay, the area is office rate. That's two area using from below and in front because you can imagine them as particles. The bigger the faster it is, in the bigger the area of surface area exposed, the faster the rate of evaporation. What do I mean? Let's just use the scruffy. Imagine the water, the the water droplets are all clumped together. It's quite difficult for them to escape. So, imagine in a room of people all clumped together, if you want to go through a narrow door, it is quite difficult. You need to take turns, it's slower. But if you spray everybody out and you have a lot more exit doors, everybody can run out at the same time. Therefore, if you open up your clothes in order to dry, you don't dry the clothes in a lump. You spread it out. Let the water droplets, the the evaporation will be faster.
Okay, so he imagined it as human beings trying to escape, right? So, yeah, leap acute particles instead. The presence of wind are stronger than faster. Why is that so? Because again, you imagine they want to escape. So, eat there, every time they want to escape, the second layer wants to escape, the first layer is to dad. There is no way that second layer can escape. So, you imagine you get rid of the first layer, the second layer can escape. Which is why, how do you get rid of the person layer? Then presence of wind. We have to blow these particles away or blow these little human beings away so that the second level can escape. So, imagine it this way.
Okay, surrounding temperature again. Just now I mentioned if you have heat, is gaining heat, evaporation will increase, isn't it? So, the more the higher the temperature, the higher the amount of heat energy available for the water vapor, for the water droplets together, and then they will fly out even faster. So, the higher the temperature, the higher the faster the rate of evaporation.
Humidity. It is actually not in the syllabus for some schools to teach it. Okay, it is good information for you. Humidity level is the rate. Okay, the amount of what a water vapor in the air. So, for example, a humid day will be man is very cloudy, a rainy day, human, rainy day, cloudy day, it will result in a lower evaporation. It will feel hotter for all of us when it's very humid because there's a high water vapor content in the air. And because of that, the evaporation of our stretch cannot take place because imagine there's a lot of vapors all all over our water from our skin cannot rise up, it cannot evaporate because evaporation of sweat takes heat away from our body, right? The gain heat from our body. The water vapor, the water droplets gain heat from our body in order to rise up to evaporate, right? But because there is so much particles here, let me show you. Because there is so much particles all around. Oops. Okay, this because there's so much. So, imagine this are the air particles. Okay, it's blocking an evaporation from the, let's say your sweat. Okay, so because it's blocking, this sweat will not be able to take away heat from our body and therefore making you cool. Therefore, on a humid day where there's a lot of water vapor in the air, evaporation decrease. You will feel warmer. But if there is less of this. Okay, so if there is less of this water vapor in the air, there will be more evaporation taking place. Therefore, you will be able to feel cooler because the sweat, as it evaporates, it takes heat away from your body.
Okay, so imagine it this way again. Same thing is at the entrance. If there is more insurance, more exit point, then there is more people who can escape, correct?
Okay, so what else do you need to know in the water chapter? You need to know the water cycle. Okay, where does the water cycle start from? There is no stuck point, there is no end point because it's a cycle, right? Okay, but well, we will look at it from this way first. Let's look at precipitation first. Precipitation is any kind of rainfall. You can say snowfall is also a couple more precipitation. Hail is also a form of precipitation. Anything that draws on the sky, generally, right? You know, form of water in different states. Okay, here will be solid state, and snow will be solid state, and rain will be liquid state.
Okay, so precipitation drops down and then there will be surface runoff. Sometimes there is underground surface runoff as well because they will get all the way down into the soil, into the drain, and it runs off and then they would gather. This is called accumulation in the sea. It doesn't have to be sick and we drain as one. Can be laying me, pony, can be anything. Okay, am I right so far?
Okay, so and then what happens when it is accumulation? So, they will continue the game here and then they will rise up again. That's why it's called a cycle. Okay, so they rise up, they will go into evaporation. Meanwhile, some of the water will be used by human beings, by any moans, but for anything and used as a form of energy. And some of them will evaporate back and then they were condensed upon touching the core surface of the condensation nuclei in the sky because it's cooler up there, right? In the sky is much. So, they were touch all this condensation nuclei, nuclei in condensation. You can't give me anything. Can be pollution, can be just a part because it can be anything as long as it's cooler. They were touched and then they were condensed. They walk on water droplets. They were clung together. They are all in the sky still. And when they get heavy enough, they will pop back down as precipitation.
So, what's that? This side is of course, there's condensation as well. Okay, so another part of condensation and a part of the water vapor that comes. It doesn't come from precipitation, doesn't come from accumulation. It comes from the trees. Okay, the trees transpire and they let out water vapor. Okay, and this contributes to the water cycle as well.
Okay, so that's all you need to know for the water chapter, for P5 signs. Let me show you some examples so you will know how to answer some questions.
Okay, so now we are looking at some of these questions over here. David set up my experiment has shown below. He placed lids at different temperatures on top of each beaker. So, you notice that okay, this little eye basically covers. So, this lid is sunny cooler. This lid is slightly higher temperature, 60 degrees Celsius. So, you can imagine this one is placed in a fridge. This one is a maybe placed over the fire. Both water is an 80 degrees Celsius. This is set up X, this is set up Y.
Okay, so the water is actually quite hot. When water is quite hot, water vapor, water droplets were actually gain energy to evaporate. They were, they will rise up even faster. Remember, he actually increases the rate of evaporation. This is something that you learned just now. So, all this already in your minds, your reading this. So, this is cooler. So, when the water vapor touches the cool surface, what happens? They will condense. Right? So, after 10 minutes, David noticed water droplets forming on the underside of both leads. That means there's water droplets here and water droplets here. So, based on his observation, he drew the water droplets formed on the underside of the lead in set up Y, but he didn't draw anything for X.
Okay, so now the question comes. State if the number of water droplets formed on the underside of the lead in set up X over here will be more than this or less than this or the same amount or as this. On the underside of the leading set up Y. So, one is an answer straight away. You know the colder it is, the faster you'll be able to gain energy from the water vapor over here, therefore increasing the rate of condensation here. Right? So, therefore, there will be more water droplets definitely. So, this answer is more. Right? More than over here because this is hot, right? So, this is cooler. It takes away more energy from them. It takes away more energy from more particles. Therefore, there will be more liquid. We know it's slowing down. Imagine, oh, yeah, release and I get touch cold. So, cold and then they slow down. They become liquid. So, imagine it that way.
So, how do you explain the answer then? Very simple. So, the lead in set up X is colder than the lead in set up Y. So, this part you need to have the keyword over there. It is colder. So, the water vapor in a beaker do this more heat. Okay, so this is another keyword. It loses more heat. So, remember, just I say in water questions, you actually need to use the word heat a lot. So, you need to take note of that. To the underside that the upon touching. So, this touching the cooler surface is again another keyword because the touching of the cooler surface explains the condensation. So, do you then need to talk about the rate of condensation? Of course, you need to say that therefore, it increases the rate of condensation. If you want to be a little bit more a long window, therefore increasing the rate of convention, therefore, there is more water droplets under the lid etcetera X.
Okay, now let's go on to the next question. Very, very similar question. Is you can see very, very common format of asking. A group of students perform an experiment to obtain pure water from seawater by using a setup as shown in the diagram below. Okay, so why is it that they can obtain pure water from seawater? From condensation or evaporation? Because only water can evaporate and only water condenses. Okay, so of course, but evil condensation, it happens on the condensation nuclei points on the pollutants in the sky. So, there is a very bad pollutants in the sky, then this water vapor will rise up and connect to this condensation nuclei, actually pollution. They will increase the acidity of the water as it drops down, therefore forming acid rain. Again, this would be a P6 topic already. So, you will read this. Oh, you ever study this in the following year.
Okay, so now let's get back to the question. So, there is plastic sheet and then there is ice cubes. There is forming down over here. So, this is the three thousand milliliters of water, sea water, and glass hang, and this is the beaker. So, they are telling you after two hours, five hundred milliliters of pure water was found in the beaker. How did that happen? Is it because there is holes in the cup or something deep inside or what? Where did this water come from?
Okay, so you have learned about the water cycle. So, what happens is this is like a little mini water cycle on display over here. What happens is this water over here will rise up. They evaporate, correct? So, once they evaporate, what happens? They will touch the cool surface. Remember, when there's gas, there's a lot of energy. They will getting a lot of energy. They will rise off. Yeah, but the moment it touched a cooler place, the ruko and then they will slowed down and then it'll become water droplets. And as they gathered more and more and more, they become heavy. They will drop down into the beaker due to this gravity over here. You pull it down, correct? And then they will all drop because of the anger. They will all drop into the beaker. So, that's how pure water is obtained.
So, how do you put it now? In simple English, then it would be like this. The molecules in the sea want to gain energy. Okay, so over here, you can see gain heat as well, if you would like to. There will be one keyword. And evaporate that. So, this is just to explain how did the water vapor come from. So, when water vapor come to contact the cooler surface, remember this keyword as well, very important. This explains how condensation happens, right? So, cooler surface is very, very important keyword. And they lost heat and condensed. So, the water vapor would touch the cool surface and it loses heat and then he will condense up into water droplets. So, when the water droplets became too heavy, they dropped into the beaker. So, that's the fall keywords that you were me all together. So, this is one, this is two, this is three, and this is four, five, sorry. Okay, so so glossy and condensed. Very, very important. We need to see all these keywords. It must be inside your answer so that you can explain the question well, right?
So, what was the purpose of placing ice cubes on the plastic? Okay, so because you need a cooler surface, therefore the ice cubes is to provide the cool surface, right? So, how do you explain that in simple English? Is like this. So, it is to cool down the plastic sheet so that condensation can take place. That so. So, what is the keyword over here? You are being too cool the plastic sheet so that condensation can take place.
Now, at the same time, another group of students did a similar experiment. The same amount of sea water and ice cubes. However, they replace the beaker with a notch basin. So, instead of a small narrow beaker, they now place a large basin into kalaiy water as shown in the diagram below. So, after two hours, only 200 milliliters of pure water was found. So, the students, they were greedy. They wanted to collect more water. So, they had bigger basin, but it actually gave them less water in the basin. And stay, what happened? Remember, the rate of evaporation is affected by four factors. Okay, so this sea water is actually evaporating. If you want the sea water to evaporate, you want this whole glass tank to have more water vapor. What should you do? The fall rates, the four factors that affects the rate of evaporation is that the bigger the surface area, the faster the evaporation, right? So, the faster the evaporation, the more water vapor there will be, the more condensation there will be. But now there is a smaller exposed surface area of the sea water. It's only nepeta speed compared to this much just now. Okay, so this small bit will affect the rate of evaporation.
So, why is the amount less? So, it will be because the surface area of the exposed, your surface area of the sea water is smaller due to the big basin taking up a huge area, and hence the rate of evaporation is slow for that two hours. So, what must you say? The exports surface area. You'll be better if you have to work exposed over here. Exposed surface area of the sea water is smaller due to the big pacing. Okay, taking up a bigger space, and hence the rate of evaporation is slower. So, for one month, these two keywords will be enough. Hmm.
Okay, another question. There shows the water cycle and the drying of the wet t-shirt. Okay, so this water cycle is just to tap on a memory, the big if you little bit assistance to let you know. Okay, this topic is the water cycle topic. Right? Name the process that is found in both the water cycle and the drying of the wet t-shirt. Remember, what is the meaning of process? Process of evaporation, condensation, melting, I'm sorry, solidifying. These are the processes. So, in this case, what is the process that is found in both the water cycle and the drying of the wet t-shirt? The drying of the wet t-shirt will definitely be evaporation. It cannot be condensation. Condensation causes wetness, isn't it? Causes water droplets. So, this one is drying. It has to be evaporation.
So, the pupa commented that a water from the wet t-shirt will eventually fall as rain. Explain why. So, basically, what they're asking you is to explain the entire water cycle. Why is that so? Because the water from the t-shirt will evaporate and then it will reach a cool surface in the sky and then they were condensed and from clouds and then they will when they close to heavy, they will fall as rain. That's how you explain a whole sequence, right?
Okay, so let's see what are the key words that we need to include over here. After the water from a wet t-shirt, so you need all these keywords. Evaporates into water vapor. The water vapor will rise. Okay, so this one is important. Evaporation. Water vapor will rise and eventually condense. Another process keyword. And from clouds. When the clouds are too heavy. Okay, the weight will cause it to fall as rain. So, these are the keywords that you will need. The two processes, evaporation, condensation. The water vapor will rise and then how it drops. So, that's how you're completely and answer this rain part.
Okay, so let's look at the last question over here. Something a little bit different. Melvin had two identical trees. Okay, this is a trick. And he mentioned is iron wrought. It looks like iron wrought, but actually maybe because from the side view, it is actually a tree. So, he placed Reiki in a freezer. So, this is extremely cold. P is co for a few hours before setting up the experiment below. So, this one doesn't say anything. So, we assume is room temperature. So, there is he here. That means this seawater is being boiled. Okay, so as this is being boiled, what happens to the water? So, straight away in your mind, you know when this is being boiled, they will be evaporation because they will gain heat and and it will trial. And then what happens when you touch the cold surface over here? They will oak on their Zuko and then you become water and then they will drip down into this beaker. A therefore, there's more water here and then there is less over here because it's not that cold, less condensation. And then there's less water here. Voila, you've got the answer already. But of course, let's see what are they actually asking for.
So, these are the top process that you have in your mind as you see questions. All this will help you to answer whatever comes next. So, Melvin poured some seawater into a flask and okay, all explaining here over here and attach the teacher to it. Okay, this is the teacher over here. He then placed the two trays P and Q and equal distances at the ends of the teacher over here. Alright, he heated the seawater until it came to a boil. So, this became boiling after a few minutes and observed some water is collected in both beakers and VX. Oh, and I've explained right? So, this is whatever I've explained written over here.
So, based on experiments, stay the process happening on trays P and Q. So, what exactly is the process happening there over here? This will be evaporation. Remember, just I say over here will be condensation. So, what is the process? Remember, process means condensation, evaporation, solidification, melting. These are the process. Explain why there was more water collected in picker A than in picker B. So, just not already explained to you. So, let's see how would you write it in simple English with the keywords inside, of course.
Okay, so tray P is a cooler surface than tray A. So, again, the work who, very, very important. Your answer. Then trick use or a warm water vapor coming out from the tea tree will lose heat. Remember, all these keywords I mentioned just now in water questions, you need to have Lucy, gain heat, cooler will explain the condensation. So, the rate of condensation over here at P becomes faster. Okay, so read a combination and that Akira is faster. That's having more water droplets because there's more condensation, there's more more the droplets. That's how you explains it. Similar, very, very similar keywords kids popping up. So, these are the basic keywords you need to know.
After some time, have been observed that a warmer water in each beaker did not increase as quickly as before. Any more? Oh, why? Why did the rate of organization stop increasing over here? Rather, it stopped having more here than here? What is the reason? Very simple because tray P is losing, or rather, is gaining heat. Is losing a coolness, is gaining heat because as it gets heat up by the water droplets over here, there is actually call the water vapor. There's actually hot, sorry. The moppet paper coming out from his action hot. He was slowly allowed this tray P to gain a lot of heat. Is a net. So, therefore, as the heat, as the tray gains here, there will be less condensation.
So, how would you explain it over here? It will be that the trees gain heat from the water, warm water vapor, and the temperature difference between the trees and a water vapor will decrease. Therefore, the rate of condensation decrease and therefore less water drop down. What are the key words again? Gain heat over here, definitely. Gain heat. Loose heat is a key word for water chapter. Okay, so the warm water vapor and the temperature difference from the trees and a water vapor would decrease. Okay, so the temperature difference is one keyword over here. You can also say the temperature difference there will be lower temperature difference or rather the temperature will balance up to you. Doesn't matter. Okay, basically, what you need to say that Kyra is game heat, right? So, the rate of condensation will decrease. So, this is the two keywords that you need. This is just an explanation over here. You can write it any how that you like it, whether the temperature became balanced or there is no more difference in temperature, up to you. So, again, heat rays gain heat, the rate of condensation will decrease. And use something in between to answer to explain this will be the complete answer for this question.
Alright, I hope you learned a lot from this chapter from my explanation. There's recurring keywords that you need to know in science. It's always these keywords that you need to put into your answer in order to score the whole point. No need to be no too long-winded. Keywords are the most important. Okay, thank you so much for tuning in. Please subscribe to our YouTube channel for more videos coming up. See you over. Bye.