[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.60,0:00:02.85,Default,,0000,0000,0000,,- [Instructor] When we add\Nsome food color to water
Dialogue: 0,0:00:02.85,0:00:04.95,Default,,0000,0000,0000,,and stir it,
Dialogue: 0,0:00:04.95,0:00:07.38,Default,,0000,0000,0000,,you see that the food\Ncolor mixes very nicely,
Dialogue: 0,0:00:07.38,0:00:09.15,Default,,0000,0000,0000,,spreads throughout the water.
Dialogue: 0,0:00:09.15,0:00:11.52,Default,,0000,0000,0000,,But now let's add some oil to the water,
Dialogue: 0,0:00:11.52,0:00:13.95,Default,,0000,0000,0000,,stir it, stir it hard.
Dialogue: 0,0:00:13.95,0:00:16.29,Default,,0000,0000,0000,,And what we find is that,
Dialogue: 0,0:00:16.29,0:00:19.17,Default,,0000,0000,0000,,hey, that oil is not mixing\Nthroughout the water.
Dialogue: 0,0:00:19.17,0:00:21.00,Default,,0000,0000,0000,,It's not spreading throughout the water.
Dialogue: 0,0:00:21.00,0:00:22.98,Default,,0000,0000,0000,,So look, in both cases we mix things,
Dialogue: 0,0:00:22.98,0:00:25.80,Default,,0000,0000,0000,,but the two mixtures look very different.
Dialogue: 0,0:00:25.80,0:00:27.57,Default,,0000,0000,0000,,And this difference is\Nimportant in chemistry.
Dialogue: 0,0:00:27.57,0:00:29.04,Default,,0000,0000,0000,,So let's talk about them.
Dialogue: 0,0:00:29.04,0:00:30.27,Default,,0000,0000,0000,,Before we talk about mixtures,
Dialogue: 0,0:00:30.27,0:00:32.25,Default,,0000,0000,0000,,Let's quickly recap pure substances.
Dialogue: 0,0:00:32.25,0:00:34.92,Default,,0000,0000,0000,,Pure substances can either be elements
Dialogue: 0,0:00:34.92,0:00:37.68,Default,,0000,0000,0000,,which are basically made\Nof one kind of atoms.
Dialogue: 0,0:00:37.68,0:00:39.57,Default,,0000,0000,0000,,These are the elements that\Nyou find in the periodic table.
Dialogue: 0,0:00:39.57,0:00:42.63,Default,,0000,0000,0000,,For example, look, oxygen\Nis made of all oxygen atoms.
Dialogue: 0,0:00:42.63,0:00:45.54,Default,,0000,0000,0000,,You have gold, which is\Nall made of gold atoms.
Dialogue: 0,0:00:45.54,0:00:48.18,Default,,0000,0000,0000,,Or they can be compounds
Dialogue: 0,0:00:48.18,0:00:51.51,Default,,0000,0000,0000,,where two or more atoms are\Nchemically bonded together
Dialogue: 0,0:00:51.51,0:00:53.16,Default,,0000,0000,0000,,in fixed ratios.
Dialogue: 0,0:00:53.16,0:00:54.90,Default,,0000,0000,0000,,For example, in water molecules,
Dialogue: 0,0:00:54.90,0:00:58.44,Default,,0000,0000,0000,,we always have two hydrogens\Nfor every one oxygen.
Dialogue: 0,0:00:58.44,0:01:00.27,Default,,0000,0000,0000,,We call these pure substances,
Dialogue: 0,0:01:00.27,0:01:02.64,Default,,0000,0000,0000,,because, well, they're purely\Nmade of the same stuff.
Dialogue: 0,0:01:02.64,0:01:03.93,Default,,0000,0000,0000,,This is purely made of oxygen.
Dialogue: 0,0:01:03.93,0:01:05.70,Default,,0000,0000,0000,,This is purely made of gold.
Dialogue: 0,0:01:05.70,0:01:07.95,Default,,0000,0000,0000,,This is purely made of water molecules.
Dialogue: 0,0:01:07.95,0:01:10.08,Default,,0000,0000,0000,,This is purely made of carbon dioxide.
Dialogue: 0,0:01:10.08,0:01:13.50,Default,,0000,0000,0000,,So elements and compounds\Nare pure substances,
Dialogue: 0,0:01:13.50,0:01:17.52,Default,,0000,0000,0000,,and they have very specific\Nproperties like boiling points,
Dialogue: 0,0:01:17.52,0:01:20.04,Default,,0000,0000,0000,,melting points, densities and so on.
Dialogue: 0,0:01:20.04,0:01:21.00,Default,,0000,0000,0000,,Now, what do you think happens
Dialogue: 0,0:01:21.00,0:01:24.18,Default,,0000,0000,0000,,when we physically combine\Ntwo pure substances,
Dialogue: 0,0:01:24.18,0:01:27.36,Default,,0000,0000,0000,,like, for example, oxygen\Nand carbon dioxide,
Dialogue: 0,0:01:27.36,0:01:29.79,Default,,0000,0000,0000,,or let's say we put gold in water.
Dialogue: 0,0:01:29.79,0:01:32.61,Default,,0000,0000,0000,,We create mixtures.
Dialogue: 0,0:01:32.61,0:01:34.56,Default,,0000,0000,0000,,A mixture is a physical combination
Dialogue: 0,0:01:34.56,0:01:37.74,Default,,0000,0000,0000,,of two or more substances\Nin any proportion you want.
Dialogue: 0,0:01:37.74,0:01:40.80,Default,,0000,0000,0000,,But wait a second, aren't\Ncompounds also mixtures?
Dialogue: 0,0:01:40.80,0:01:43.47,Default,,0000,0000,0000,,I mean, here, carbon and\Noxygen are mixed together.
Dialogue: 0,0:01:43.47,0:01:45.18,Default,,0000,0000,0000,,Hydrogen and oxygen are mixed together.
Dialogue: 0,0:01:45.18,0:01:47.37,Default,,0000,0000,0000,,So shouldn't these be mixtures as well?
Dialogue: 0,0:01:47.37,0:01:49.86,Default,,0000,0000,0000,,No, and this used to\Nconfuse me a lot, okay?
Dialogue: 0,0:01:49.86,0:01:52.02,Default,,0000,0000,0000,,but the key point is you get mixtures
Dialogue: 0,0:01:52.02,0:01:54.84,Default,,0000,0000,0000,,when you physically combine\Ntwo or more substances.
Dialogue: 0,0:01:54.84,0:01:56.97,Default,,0000,0000,0000,,And as a result, because these substances
Dialogue: 0,0:01:56.97,0:01:59.61,Default,,0000,0000,0000,,have different boiling,\Nmelting points and densities,
Dialogue: 0,0:01:59.61,0:02:01.68,Default,,0000,0000,0000,,you can physically separate them.
Dialogue: 0,0:02:01.68,0:02:05.16,Default,,0000,0000,0000,,For example, I can just pick\Nthis cold bar out from water.
Dialogue: 0,0:02:05.16,0:02:07.56,Default,,0000,0000,0000,,But in other cases, I can\Nheat them or cool them
Dialogue: 0,0:02:07.56,0:02:09.90,Default,,0000,0000,0000,,or spin them or use magnets,
Dialogue: 0,0:02:09.90,0:02:11.46,Default,,0000,0000,0000,,if they have magnetic properties,
Dialogue: 0,0:02:11.46,0:02:13.98,Default,,0000,0000,0000,,but all by physical means,\NI can separate them.
Dialogue: 0,0:02:13.98,0:02:15.60,Default,,0000,0000,0000,,But in contrast,
Dialogue: 0,0:02:15.60,0:02:19.17,Default,,0000,0000,0000,,compounds are where atoms\Nare chemically combined,
Dialogue: 0,0:02:19.17,0:02:21.12,Default,,0000,0000,0000,,they're chemically bonded together.
Dialogue: 0,0:02:21.12,0:02:25.68,Default,,0000,0000,0000,,You cannot separate these\Natoms by physical processes.
Dialogue: 0,0:02:25.68,0:02:28.53,Default,,0000,0000,0000,,So compounds are still pure substances.
Dialogue: 0,0:02:28.53,0:02:30.96,Default,,0000,0000,0000,,Now, guess what? Even mixtures\Ncan have different types.
Dialogue: 0,0:02:30.96,0:02:32.76,Default,,0000,0000,0000,,So let's investigate\Nthem a little bit more.
Dialogue: 0,0:02:32.76,0:02:36.93,Default,,0000,0000,0000,,Here we have mixed oxygen\Ngas and carbon dioxide gases.
Dialogue: 0,0:02:36.93,0:02:38.19,Default,,0000,0000,0000,,When you do that,
Dialogue: 0,0:02:38.19,0:02:40.89,Default,,0000,0000,0000,,the different substances\Nget evenly distributed
Dialogue: 0,0:02:40.89,0:02:43.68,Default,,0000,0000,0000,,at a molecular level; and as a result,
Dialogue: 0,0:02:43.68,0:02:46.86,Default,,0000,0000,0000,,the composition stays pretty\Nmuch the same throughout.
Dialogue: 0,0:02:46.86,0:02:49.59,Default,,0000,0000,0000,,You get a uniform composition throughout.
Dialogue: 0,0:02:49.59,0:02:53.34,Default,,0000,0000,0000,,And you cannot see any\Ndistinct parts or phases
Dialogue: 0,0:02:53.34,0:02:54.45,Default,,0000,0000,0000,,with the naked eye.
Dialogue: 0,0:02:54.45,0:02:56.13,Default,,0000,0000,0000,,And that's exactly what happened
Dialogue: 0,0:02:56.13,0:02:58.71,Default,,0000,0000,0000,,when we added food color to our water.
Dialogue: 0,0:02:58.71,0:03:02.43,Default,,0000,0000,0000,,Again, the food color\Nuniformly distributed itself
Dialogue: 0,0:03:02.43,0:03:04.50,Default,,0000,0000,0000,,throughout the water at a molecular level;
Dialogue: 0,0:03:04.50,0:03:06.57,Default,,0000,0000,0000,,and as a result, see,\Nyou cannot distinguish
Dialogue: 0,0:03:06.57,0:03:09.75,Default,,0000,0000,0000,,where the food color is and\Nwhere the water is, right?
Dialogue: 0,0:03:09.75,0:03:12.78,Default,,0000,0000,0000,,We call such mixtures\Nhomogeneous mixtures.
Dialogue: 0,0:03:12.78,0:03:14.16,Default,,0000,0000,0000,,So homogeneous mixtures are the one
Dialogue: 0,0:03:14.16,0:03:15.60,Default,,0000,0000,0000,,where you cannot distinguish
Dialogue: 0,0:03:15.60,0:03:18.06,Default,,0000,0000,0000,,between the different\Nsubstances that are mixed.
Dialogue: 0,0:03:18.06,0:03:21.60,Default,,0000,0000,0000,,In contrast. Look at\Nthe gold inside water.
Dialogue: 0,0:03:21.60,0:03:25.44,Default,,0000,0000,0000,,I can clearly see where the\Ngold is and where the water is.
Dialogue: 0,0:03:25.44,0:03:28.68,Default,,0000,0000,0000,,I can see the boundary over here nicely.
Dialogue: 0,0:03:28.68,0:03:32.10,Default,,0000,0000,0000,,And the same thing happens\Nwhen we add oil in water.
Dialogue: 0,0:03:32.10,0:03:34.29,Default,,0000,0000,0000,,I can clearly see there's oil here
Dialogue: 0,0:03:34.29,0:03:36.15,Default,,0000,0000,0000,,and there's water over there.
Dialogue: 0,0:03:36.15,0:03:37.74,Default,,0000,0000,0000,,Here, look, the substance
Dialogue: 0,0:03:37.74,0:03:40.71,Default,,0000,0000,0000,,is not evenly distributed throughout.
Dialogue: 0,0:03:40.71,0:03:42.48,Default,,0000,0000,0000,,There is nonuniform distribution.
Dialogue: 0,0:03:42.48,0:03:45.09,Default,,0000,0000,0000,,There's a lot of oil here and\Nhardly anything over here.
Dialogue: 0,0:03:45.09,0:03:47.88,Default,,0000,0000,0000,,There's a lot of gold here\Nand nothing over here.
Dialogue: 0,0:03:47.88,0:03:50.28,Default,,0000,0000,0000,,Such mixtures where we can easily make out
Dialogue: 0,0:03:50.28,0:03:52.86,Default,,0000,0000,0000,,the different substances\Nthat are mixed together,
Dialogue: 0,0:03:52.86,0:03:54.93,Default,,0000,0000,0000,,which we can see with naked eye,
Dialogue: 0,0:03:54.93,0:03:58.29,Default,,0000,0000,0000,,we call them heterogeneous mixtures.
Dialogue: 0,0:03:58.29,0:04:00.51,Default,,0000,0000,0000,,Alright, let's take some examples now.
Dialogue: 0,0:04:00.51,0:04:02.01,Default,,0000,0000,0000,,Why don't you pause the video,
Dialogue: 0,0:04:02.01,0:04:03.84,Default,,0000,0000,0000,,go through each one of\Nthem and classify them
Dialogue: 0,0:04:03.84,0:04:06.90,Default,,0000,0000,0000,,as either homogeneous mixtures\Nor heterogeneous mixtures.
Dialogue: 0,0:04:06.90,0:04:08.31,Default,,0000,0000,0000,,Pause and try.
Dialogue: 0,0:04:08.31,0:04:10.23,Default,,0000,0000,0000,,Alright, let's look at salads first.
Dialogue: 0,0:04:10.23,0:04:12.15,Default,,0000,0000,0000,,I can clearly see the different options
Dialogue: 0,0:04:12.15,0:04:13.02,Default,,0000,0000,0000,,that are mixed together.
Dialogue: 0,0:04:13.02,0:04:15.03,Default,,0000,0000,0000,,I can clearly see their boundaries.
Dialogue: 0,0:04:15.03,0:04:17.64,Default,,0000,0000,0000,,So this is a heterogeneous mixture.
Dialogue: 0,0:04:17.64,0:04:19.50,Default,,0000,0000,0000,,Okay, what about butter caramel.
Dialogue: 0,0:04:19.50,0:04:21.36,Default,,0000,0000,0000,,Well, can we see distinctly
Dialogue: 0,0:04:21.36,0:04:22.98,Default,,0000,0000,0000,,where the butter is and\Nwhere the caramel is?
Dialogue: 0,0:04:22.98,0:04:25.74,Default,,0000,0000,0000,,No, they're nicely uniformly distributed.
Dialogue: 0,0:04:25.74,0:04:28.47,Default,,0000,0000,0000,,So this is a homogeneous mixture.
Dialogue: 0,0:04:28.47,0:04:31.50,Default,,0000,0000,0000,,We can clearly see the seashells\Nand the cement separately.
Dialogue: 0,0:04:31.50,0:04:33.78,Default,,0000,0000,0000,,So it is heterogeneous mixture.
Dialogue: 0,0:04:33.78,0:04:34.80,Default,,0000,0000,0000,,This is sand and water.
Dialogue: 0,0:04:34.80,0:04:36.75,Default,,0000,0000,0000,,We can see the sand here\Nand water over here.
Dialogue: 0,0:04:36.75,0:04:37.89,Default,,0000,0000,0000,,I can clearly see the boundaries.
Dialogue: 0,0:04:37.89,0:04:40.35,Default,,0000,0000,0000,,So it's again heterogeneous mixture.
Dialogue: 0,0:04:40.35,0:04:41.64,Default,,0000,0000,0000,,What about ink?
Dialogue: 0,0:04:41.64,0:04:43.50,Default,,0000,0000,0000,,Well, over here there's\Na uniform distribution.
Dialogue: 0,0:04:43.50,0:04:45.84,Default,,0000,0000,0000,,I cannot see any boundaries,\Nany distinctions.
Dialogue: 0,0:04:45.84,0:04:48.24,Default,,0000,0000,0000,,This is a uniform distributed mixture,
Dialogue: 0,0:04:48.24,0:04:50.49,Default,,0000,0000,0000,,so this is a homogeneous mixture.
Dialogue: 0,0:04:50.49,0:04:51.99,Default,,0000,0000,0000,,What about brass?
Dialogue: 0,0:04:51.99,0:04:52.95,Default,,0000,0000,0000,,Hmm, this could be tricky.
Dialogue: 0,0:04:52.95,0:04:54.12,Default,,0000,0000,0000,,What exactly is brass?
Dialogue: 0,0:04:54.12,0:04:57.60,Default,,0000,0000,0000,,Well, brass is a combination\Nmostly of copper and zinc.
Dialogue: 0,0:04:57.60,0:05:00.51,Default,,0000,0000,0000,,But look, it is mixed uniformly.
Dialogue: 0,0:05:00.51,0:05:03.00,Default,,0000,0000,0000,,I cannot see the distinction\Nbetween copper and zinc.
Dialogue: 0,0:05:03.00,0:05:05.67,Default,,0000,0000,0000,,And so this is again\Na homogeneous mixture.
Dialogue: 0,0:05:05.67,0:05:07.83,Default,,0000,0000,0000,,Finally, what about copper?
Dialogue: 0,0:05:07.83,0:05:09.75,Default,,0000,0000,0000,,Hmm, well, this is a trick question
Dialogue: 0,0:05:09.75,0:05:11.58,Default,,0000,0000,0000,,because copper is an element,
Dialogue: 0,0:05:11.58,0:05:13.08,Default,,0000,0000,0000,,it's not a mixture at all.
Dialogue: 0,0:05:13.08,0:05:14.64,Default,,0000,0000,0000,,It's a pure substance.
Dialogue: 0,0:05:16.11,0:05:17.43,Default,,0000,0000,0000,,So in summary, when you combine
Dialogue: 0,0:05:17.43,0:05:19.14,Default,,0000,0000,0000,,two or more substances physically,
Dialogue: 0,0:05:19.14,0:05:20.55,Default,,0000,0000,0000,,we call them mixtures.
Dialogue: 0,0:05:20.55,0:05:23.82,Default,,0000,0000,0000,,If the substances are mixed\Nuniformly at a molecular level
Dialogue: 0,0:05:23.82,0:05:26.28,Default,,0000,0000,0000,,so you cannot distinctly\Nsee the different parts,
Dialogue: 0,0:05:26.28,0:05:28.71,Default,,0000,0000,0000,,we call them homogeneous mixtures.
Dialogue: 0,0:05:28.71,0:05:30.48,Default,,0000,0000,0000,,In contrast, if the different components
Dialogue: 0,0:05:30.48,0:05:32.67,Default,,0000,0000,0000,,are not uniformly distributed
Dialogue: 0,0:05:32.67,0:05:34.50,Default,,0000,0000,0000,,and you can distinctly see them,
Dialogue: 0,0:05:34.50,0:05:36.54,Default,,0000,0000,0000,,you might even see their boundaries,
Dialogue: 0,0:05:36.54,0:05:39.15,Default,,0000,0000,0000,,we call them heterogeneous mixtures.