Okay, let's talk about now, for the last video of the morning, the difference between a pure substance and a mixture. Okay, so you can see here, we've got in the picture four pure substances, and there are various types of compounds. I know you don't know much about compounds yet, or atoms, elements, one of them is. But you'll learn more and more as things go on. So for right now, let's just concentrate on the pure substance mixture thing, okay? So most of the things that you see in the world are mixtures. In fact, it takes work to get a pure substance out of a mixture. It's like, I don't know, if you have a jar of change, right? That's a mixture of pennies and nickels and quarters and things like that. And if you wanted to only get the dimes out, you would have to do some work to actually extract those dimes from the rest of the change bucket, okay? So that's what somebody has done, previous, not myself, to me demonstrating this. So I could actually have pure copper, pure sodium chloride, pure sucrose, which is essentially table sugar. This is essentially table salt and pure oleic acid, which is the major component of corn oil. So we also have another substance here, deionized water, which is pure water, okay? So those are all pure substances. And let's do the reverse, you know? So let's put these things back into a mixture, okay? So let's go about and look at the different kinds of mixtures you can get from these substances. So let's put some of this copper shot into here, okay? So you can see we've got it in a beaker now. Hopefully you can see that it's still on camera. And now we'll put some deionized water in there, okay? So now we've got a mixture of those two pure substances, copper and deionized water, okay? So here's the mixture of those two substances. Hopefully you can see, well, what we say is the copper did not dissolve into the water. So we've got a mixture, but it's a heterogeneous mixture, okay? So hopefully you can see that. Okay, so let's do the same thing with sodium chloride and water, okay? So let's pour a little bit of the sodium chloride. So remember this is just regular table salt. This is actually pure stuff that I got from the chemical company. So pour a little bit of water in there, we'll mix it up.  Put some more water in there. So you can see hopefully now, so this is an ionic compound, and this is typical of ionic compounds. Some ionic compounds won't do this, and we'll talk about those later when we get to the solubility chapter. But you can see there, hopefully, that we've made a mixture that looks quite different than the two components individually, okay? So I guess it looks very much like the pure water, which is the solvent, which you'll learn about later, but it looks very little like sodium chloride. But if I were to taste it, it would taste a lot like sodium chloride. So mixtures have the components or properties of both of the components of that mixture. This actually is different than this mixture, hopefully you can see, because you can't see the sodium chloride particles anymore in there. But you know they're in there because the properties are still being shown, right? See, you can still see the copper particles here, okay? So this we call a solution, or a homogenous mixture. So in chemistry, we call homogenous mixture solutions. So heterogeneous mixture, homogenous mixture, okay? So this was an ionic compound. Now let's do a covalent compound, like sucrose, okay? So remember we said this is like pure table sugar. So let's go ahead and do the same experiment with it. Oh, and by the way, if you are wondering if this is a physical or a chemical change, all mixing of things is just a physical change. Once it starts catching on fire or bubbling or something like that, reacting, then you can call it a chemical change, okay? There's some videos on there somewhere about physical and chemical changes. So you can see this is a covalent compound, and we'll try to mix it up. So table sugar, I'm sure you guys know what's going to happen. So even though the other one was an ionic compound, and this is a covalent compound, they still exhibited that same property of being what we call soluble in water. And that's due to the chemical structure of them, they're both molecular solids that are polar. So sucrose is very polar, and water is very polar, both molecular solids. You'll learn more about that later, but you can see, right, we mix them up, right? And again, just like this one, you can't really see the sugar anymore. You can't see it at all. But if I were to taste it, it would be sweet. So it still has that property of sugar. So we know this is the mixture, but since we can't see the sugar particles anymore, we call it a homogenous mixture. And again, homogenous mixtures, we call solutions in chemistry. So we've got a heterogeneous mixture when we mixed copper and water, a homogenous solution when we mixed sodium chloride, which is an ionic compound, and a homogenous mixture when we mixed sucrose, or a solution when we mixed sucrose. So let's see what happens when we mix oleic acid. So oleic acid is also covalent or molecular compound. So very much like sucrose, very much like water. So if we were to just compare it with what happened to sucrose, we would expect it to dissolve as well. But what happens, here, let's show you, put the oleic acid in. So this is essentially the major component of corn oil, or a major component of corn oil. And let's mix it with water and see what happens. So we made a mixture, but hopefully you guys can see that it's not a homogenous mixture, right? The oleic acid has made a layer. Let me get this. Has made a layer on top of the water. So that's still a mixture, but it's a heterogeneous mixture, sorry. And the reason they don't dissolve in each other is, unlike sucrose, oleic acid, so oleic acid is a non-polar compound, sucrose is a polar compound. So well, why does sucrose dissolve in water? Well, water is polar and things that look very much like other things dissolve in them. So there's a rule that we say like dissolves like, and if you can remember that for later, it'll really help you out. So we'll talk more about this solution stuff and like dissolves like, but the mixture part of this video is the most important for you guys who are doing chapter one right now. So just to rehash heterogeneous mixture, so you can still see the different components of the mixture, homogenous mixture, homogenous mixture, heterogeneous mixture. So remember, mixtures, all four of them still contain properties of both of the things in the mixture. Both of these homogenous mixtures or homogenous mixtures, we call solutions in chemistry. And the reason that they've dissolved is because of two different types of properties that these compounds inherently have. Sodium chloride makes ions which dissolve into water, and sucrose itself is polar, so it dissolves into a polar covalent compound. So hopefully that helps. Let me know if you guys need any more explanation on this subject. Okay, have a good morning.


I mean, it is inconceivable for any Western democracy to subsist even for 10 years more if we didn't have, through progressive taxation, a steady transfer of resources from rich people to poor. Well, I consider that we can begin to talk about the world environment and about safeguarding our planet when we, the rich nations, are giving in perfectly formal, institutionalized tax assistance. Oh, at least 1% of our gross national product in development capital for the poor nations, I would go higher myself, you see, we've got to stop lecturing them while we sit back and in growth, 80% of the world's income for 20% of the world's people. And that, I think, is the critical thing on this development environment issue.  Because you will not create a community unless you've got some moral commitment. And moral commitment needs some very stern underpinnings because we ain't moral easy. This lecture series celebrates our founder, Barbara Ward, who was a landmark thinker and broadcaster, author of many books, including Only One Earth. Her insights on the urgent need to bring together environmental prosperity and economic well-being would be of great value as we grapple with today's difficulties in addressing poverty and climate change. So I'd like to end with two short quotes. The first reminds us of the common principles running through all human belief systems, both farmers in Ghana and native North Americans say of the earth that this land is a sacred trust placed in our care for the sake of coming generations. The second is from Barbara Ward herself, who in her book, Only One Earth, said, we have forgotten how to be good guests, how to walk lightly on the earth, as other preachers do. Let's learn to be better guests on this earth. To reach the ultimate of power which we have done, we can only respond by having the ultimate of community, which is a single planet. And that is where self-interest, moral interest, and sheer technical fact coincide. Many politicians are frightened to face their constituents with this kind of a truth. They have a fear that if they support the idea of a more equitable distribution of the world's resources and so forth, that they would not be voted back into office. What do you say to them? Well, I would say first of all that if you take some of the Western democracies, Canada, my own country, Britain, Holland, all the Scandinavian countries, France up to a point, all these countries have now formally agreed that by 1975 they will give 1% of gross national product in aid to development. And one reason why they're doing that is because their electorate would no longer accept the idea that you shouldn't do it. I recall still in my childhood in Europe how we saw black and grey and yellow chimneys billowing smoke from factory, open waste dumps in the countryside, filthy, untreated waste water running into rivers and ponds. That is not sort of the sight that my children have been sort of raised to see. This is no longer the case in most of Europe of today. And that shows us how much we can actually achieve in just one generation's time. In short, everywhere, no matter how different the countries and the societies are, this story is basically the same. As the climate changes, things become more and more unpredictable. And we can cope within the rich societies, but it's much harder if you are a developing country, if you at least develop countries. And of course, as always, the most vulnerable parts of the population will be hit the most. It seems to me that the biosphere in which we share the climate, we share systems, we share oceans, and we cannot escape it could be the physical, scientific and technical underpinning of a moral community, because we tend to be moral when we have no further choice. It is good also to participate in this ceremony, which is honored, predistinguished citizens of the free world, President Pusie, Father Bonn, and our friend from the world of freedom, Lady Jackson. So great is the shortage of capital, so obstructed are the means of development that they won't even be able to learn from our mistakes. That is the end. That would be the ultimate tragedy. I mean, for us to go and make the mistakes and then no one to learn from them, that really would be a cosmic bad joke, wouldn't it?