Properties of water 1 how is the definition of cohesion 2...

Properties of water: 1. How is the definition of cohesion? 2. What causes surface tension in water? 3. Water has a high specific heat. How does that moderate coastal temperatures? 4. What makes water a polar molecule? 5. Describe the process of evaporation and how it leads to cooling.

Transcript

00:02 Okay, today we got some questions about water.

00:06 So let's start with talking about why water is called a polar molecule.

00:11 Basically it means it has poles.

00:14 You can see right here, oxygen is negatively charged, and you can see right here, the hydrogens are positively charged.

00:25 And that is because oxygen is greedier for electrons than hydrogen.

00:32 Technically, they're sharing the same electrons, but oxygen is pulling them over to its side of the room.

00:39 And since the electrons are negatively charged, it gives the oxygen a more negative charge.

00:46 And by the same token, because the hydrogens have fewer electrons, it means they're automatically more positively charged.

00:56 So we can say that a water molecule functions like a magnet.

01:04 It's got poles just like a magnet does.

01:07 And that is why we call water a polar molecule.

01:18 Cohesion means that water likes water.

01:23 In this case, that's what it means.

01:24 Cohesion in general is talking about the attraction of molecules to other molecules of the same kind.

01:32 And we can see how that works here.

01:36 So we've got this water molecule and this water molecule.

01:41 And you can see that the positive end of the first molecule is attracted to the negative end of the other water molecule, just like magnets.

01:52 Negative opposites attract, right? and so that attraction forms what we call a hydrogen bond.

02:05 Which in turn is responsible for surface tension.

02:11 This is a glass of water, and you can see the little water molecules in there that i've drawn, and you can see that between each water molecule, there's a little h that represents a hydrogen bond.

02:25 So a glass of water is just a highly structured group of bonds, really, and so when you see an insect that's walking on a body, of water.

02:35 What they're walking on is the hydrogen bonds.

02:39 Right? it's pretty cool.

02:43 Okay.

02:44 So there's some other things.

02:47 We're going to talk about water and temperature.

02:52 So temperature, just to remind us, is the average kinetic energy of molecules...