Original video: https://youtu.be/GP1C7eHZXOY This video examines the physical and chemical properties of water that were instrumental in the formation of Earth and continue to be essential for plant life. We will discuss theories regarding the origin of water on Earth, including the bombardment by icy comets and the energetic fusion of hydrogen and oxygen. The video will then delve into the key properties of water, including hydrogen bonding, thermal conductivity, heat capacity, cohesion, adhesion, surface tension, polarity, and its role as a solvent.
Video Transcript:
So, water, H2O, where does it come from? Originally, before Earth, when Earth was first created, what was it like? Asteroids floating about. When Earth was first formed, it was just a hot molten rock. There's no life. How do we have so much water covering 2/3 of the planet? Where did it come from?
From underground. Okay, before underground, where did it come from? Can you create water? If on Earth you cannot create water, where did water on Earth come from? Do you understand my point? Where?
Asteroids. Unfortunately, we do not have a time machine to go back and see what happened 4 billion years ago. Potentially, there are two explanations. During the early formation of the Earth, there was a violent bombardment of extraterrestrial objects from open space, including ice comets. Comets are ice. Ice melts because the Earth is hot, then you get your lakes. That's one.
Another is, because of the early formation of the Earth, super-hot, that heat is actually energy, and this energy, somehow, is enough to fuse oxygen and hydrogen together. Oxygen can come about from the element before it. Look at your periodic table, you start off with, what's the first element? Hydrogen. Two hydrogens come together, what do you get? Two hydrogen, one electron, one proton. If I increase the atomic number, what do you get now?
Helium. You suddenly get a new element just by increasing the atomic number. And then this atomic number can be added because of energy, because of compression, so many things can happen. You started off with one element, now you get a new element. So oxygen not necessarily has to be created from the flick of a hand, it can come from a precursor element. So you add more electrons to the element, the valency of the electron will start to increase. You got two electrons in one valence, at the beginning, we call it the duplet, and then you got your octet, then you get some more. Eventually, you got your oxygen, hydrogen, and so many other things.
So with this, water has properties like any other things, like wood. This wood has properties. What properties does wood have? Hard, flammable. Flammable, um, that's actually for chemical compounds. Um, burnable, maybe, right? What else? Properties of wood. It can act as an insulator.
What about water? These are the common properties of water. I'm not saying this is an exhaustive list, there are many more. Water has hydrogen bonding, meaning that water can become a universal solvent because in the water molecule, you have the electronegative part and then a bit more positive part. This can somehow orient itself to get attracted to other molecules. When this happens, there's a fusion of molecules, and the molecule which was once a solid, cannot dissolve, and be part of the liquid. Easy example, sodium chloride.
Then water also has thermal conductivity, meaning that if you have a container of water, if you provide heat from one end, the heat can travel from this end to the other without you having to stir the water. Kind of like when you first learned about sound. Your teacher tells you sound can travel in solid, air, and liquid. Which sound travels the best? Solid. You can hear it.
So, water in liquid, if you put a sound wave in it, it can propagate, and the sound can reach the other end of it. The same goes for heat, the heat can travel, no need to do the stirring. And then the higher heat capacity. H2O, it is not easy to break the bond, meaning that before the bonds can be broken, a large amount of energy needs to be absorbed first. Meaning that the phases of water, from solid to liquid to vapor or steam, gas, you need lots of energy. That's why when you turn on your stove, it does your water in the kettle boil under 10 seconds? No, it takes some time. This is because it has a high heat capacity. It is able to absorb so much energy before something happens to it. And this is why your body is filled with water, and your temperature can be regulated easily. You know your temperature, what's your body temperature? 15? Are you a fish? 37. Body temperature, 37, it's easy to regulate because we are highly filled. The same thing happens to our planet. Over 2/3 of our planet is water. If this is not the case, we are pretty much going to turn into a fireball, because there is no big body to regulate our temperature.
And this is the reason when I mentioned the plants transpire, it can cool itself. Number one, it's not easy to increase the temperature of the plant because the plant is filled with water, just like humans. Secondly, the moment plants transpire, the water that leaves the plant's surface will pull along with it a large amount of heat from the plant, bring it to the atmosphere. Perfect for cooling purposes.
Cohesion, so cohesion actually should be number four, and number six kind of comes together, cohesion and adhesion. Have you learned this before? What's that, remember? Can't remember. Cohesion is the sticking of similar molecules together, hydrogen, hydrogen, water, water, wood to wood, similar molecules. Adhesion, the sticking of different material or substances coming in contact together. For example, water molecules and the xylem wall, stick to it.
So when this is translated into the water transport in plants, cohesion is causing the water to be pulled from the bottom all the way to the top. And it is also not easy for the water to come back because it is sticking to the wall of the xylem due to the force of adhesion. An easy way to remember is, cohesion is cooperation, it's easy to cooperate among your same kind, water, water, it's easy to operate. Water, xylem wall, they need to agree first before they can do cooperation.
What else? Surface tension. What's surface tension? Give me one example of surface tension in nature. Droplets on the leaf. Insects walking on the pond surface, why? Because high surface tension. Surface tension is actually the ability, it doesn't only apply to water, to any liquid. It can be ethanol, it can be sugar, it can be iodine. The ability for you to spread the solution, the liquid, before it breaks.
Since water has this hydrogen bonding, it is not easy to break the surface of it. So, water in the pond forms a form of skin on the surface that enables the insect to stride upon it, hence the name of the insect, water strider. What's it, water strider, you know, water strider, have you learned your entomology? Soon you're going to learn about that insect, and entomology, water strider.
Heat of fusion, have you learned this before? Of fusion, didn't you take your physics and biology before, or chemistry, during your form six? Okay. So, what is it actually? Changes of energy. The energy needed to change the substance from solid to liquid, from ice to water, without changing the temperature, so we call it the heat of fusion. The other one is heat of vaporization. The energy needed, used to change from liquid to vapor, without the change of temperature, okay.
What else? Um, polarity and solvent, this is actually explained in the way, polarity, because of H+ and oxygen 2, that's electronegative in the water molecule, and then solvent, because of this polarity, water is able to become the solvent. Can water dissolve sugar? Yes, pretty much, if you think about it, water can dissolve any powder, right? Yeah, except gold powder. Well, gold is an element, it's not powder, it has been powdered, right? Okay, so, uh, I'm not going to go down there, all this, all this dielectric constant, this is actually for my other class.
Keywords: Water, physical properties, Chemical properties, Earth formation, Plant physiology
Watch full video: https://youtu.be/MBSLjvlR-Tg
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