[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.18,0:00:02.25,Default,,0000,0000,0000,,- [Instructor] Ice melts\Nat 0 degrees Celsius.
Dialogue: 0,0:00:02.25,0:00:03.51,Default,,0000,0000,0000,,But if we take something like gold,
Dialogue: 0,0:00:03.51,0:00:06.87,Default,,0000,0000,0000,,then it'll melt only about\N1000 degrees Celsius.
Dialogue: 0,0:00:06.87,0:00:09.93,Default,,0000,0000,0000,,Similarly, water boils at\Naround 100 degrees Celsius.
Dialogue: 0,0:00:09.93,0:00:11.58,Default,,0000,0000,0000,,But if we take something like nitrogen,
Dialogue: 0,0:00:11.58,0:00:13.98,Default,,0000,0000,0000,,well, it'll boil at a very low temperature
Dialogue: 0,0:00:13.98,0:00:16.65,Default,,0000,0000,0000,,of -200 degrees Celsius,\Nslightly about that.
Dialogue: 0,0:00:16.65,0:00:19.35,Default,,0000,0000,0000,,But the big question is\Nwhy do different materials
Dialogue: 0,0:00:19.35,0:00:21.72,Default,,0000,0000,0000,,have different melting and boiling points?
Dialogue: 0,0:00:21.72,0:00:23.25,Default,,0000,0000,0000,,Let's find out.
Dialogue: 0,0:00:23.25,0:00:24.36,Default,,0000,0000,0000,,Now, to answer this question,
Dialogue: 0,0:00:24.36,0:00:27.15,Default,,0000,0000,0000,,we need to ask a much\Nmore fundamental question.
Dialogue: 0,0:00:27.15,0:00:29.49,Default,,0000,0000,0000,,What keeps stuff together?
Dialogue: 0,0:00:29.49,0:00:31.71,Default,,0000,0000,0000,,Well, if you were to look into, you know,
Dialogue: 0,0:00:31.71,0:00:32.54,Default,,0000,0000,0000,,if you could zoom in
Dialogue: 0,0:00:32.54,0:00:34.47,Default,,0000,0000,0000,,and look at the molecule\Nat the atomic level,
Dialogue: 0,0:00:34.47,0:00:36.36,Default,,0000,0000,0000,,we'll find that all\Nthese atoms and molecules
Dialogue: 0,0:00:36.36,0:00:38.49,Default,,0000,0000,0000,,are actually being\Nattracted to each other.
Dialogue: 0,0:00:38.49,0:00:41.73,Default,,0000,0000,0000,,There is a force of attraction\Nthat's keeping them together.
Dialogue: 0,0:00:41.73,0:00:44.10,Default,,0000,0000,0000,,In fact, you've probably\Nwitnessed this force of attraction
Dialogue: 0,0:00:44.10,0:00:46.18,Default,,0000,0000,0000,,when you've seen two drops merging to form
Dialogue: 0,0:00:46.18,0:00:48.57,Default,,0000,0000,0000,,a bigger drop, okay?
Dialogue: 0,0:00:48.57,0:00:49.77,Default,,0000,0000,0000,,So this force of attraction
Dialogue: 0,0:00:49.77,0:00:51.90,Default,,0000,0000,0000,,keeps all the particles together.
Dialogue: 0,0:00:51.90,0:00:54.27,Default,,0000,0000,0000,,And turns out that this\Nforce of attraction
Dialogue: 0,0:00:54.27,0:00:56.82,Default,,0000,0000,0000,,purely depends on the types of particles.
Dialogue: 0,0:00:56.82,0:00:58.83,Default,,0000,0000,0000,,So for example, the strength\Nof this force of attraction
Dialogue: 0,0:00:58.83,0:01:00.93,Default,,0000,0000,0000,,between water molecules would be different
Dialogue: 0,0:01:00.93,0:01:03.93,Default,,0000,0000,0000,,than that between gold atoms, right?
Dialogue: 0,0:01:03.93,0:01:05.16,Default,,0000,0000,0000,,But another thing you can see
Dialogue: 0,0:01:05.16,0:01:08.16,Default,,0000,0000,0000,,is that particles also\Nhave kinetic energy.
Dialogue: 0,0:01:08.16,0:01:10.53,Default,,0000,0000,0000,,What does that depend on?
Dialogue: 0,0:01:10.53,0:01:13.23,Default,,0000,0000,0000,,Well, kinetic energy depends\Npurely on temperature.
Dialogue: 0,0:01:13.23,0:01:14.55,Default,,0000,0000,0000,,In fact, temperature is a measure
Dialogue: 0,0:01:14.55,0:01:16.20,Default,,0000,0000,0000,,of the average kinetic\Nenergy of the particles.
Dialogue: 0,0:01:16.20,0:01:17.03,Default,,0000,0000,0000,,At high temperature,
Dialogue: 0,0:01:17.03,0:01:18.45,Default,,0000,0000,0000,,the average kinetic energy is very high.
Dialogue: 0,0:01:18.45,0:01:19.35,Default,,0000,0000,0000,,And at low temperature,
Dialogue: 0,0:01:19.35,0:01:21.03,Default,,0000,0000,0000,,the average kinetic energy is very low.
Dialogue: 0,0:01:21.03,0:01:22.80,Default,,0000,0000,0000,,Kinetic energy only\Ndepends on temperature.
Dialogue: 0,0:01:22.80,0:01:23.70,Default,,0000,0000,0000,,It has nothing to do
Dialogue: 0,0:01:23.70,0:01:25.83,Default,,0000,0000,0000,,with which particles we're dealing with.
Dialogue: 0,0:01:25.83,0:01:27.69,Default,,0000,0000,0000,,So you can see there are\Ntwo things over here.
Dialogue: 0,0:01:27.69,0:01:29.43,Default,,0000,0000,0000,,First, we have the force of attraction
Dialogue: 0,0:01:29.43,0:01:31.14,Default,,0000,0000,0000,,that's trying to keep them together.
Dialogue: 0,0:01:31.14,0:01:33.33,Default,,0000,0000,0000,,This purely depends on\Nthe type of particle,
Dialogue: 0,0:01:33.33,0:01:35.73,Default,,0000,0000,0000,,but it has nothing to do with temperature.
Dialogue: 0,0:01:35.73,0:01:38.67,Default,,0000,0000,0000,,On the other hand, we have kinetic energy
Dialogue: 0,0:01:38.67,0:01:41.34,Default,,0000,0000,0000,,that has nothing to do\Nwith the particle type,
Dialogue: 0,0:01:41.34,0:01:43.62,Default,,0000,0000,0000,,but it purely depends on temperature.
Dialogue: 0,0:01:43.62,0:01:44.45,Default,,0000,0000,0000,,And what's interesting
Dialogue: 0,0:01:44.45,0:01:46.50,Default,,0000,0000,0000,,is that these two are kind of opposite.
Dialogue: 0,0:01:46.50,0:01:48.42,Default,,0000,0000,0000,,The attraction force is\Ntrying to keep them together,
Dialogue: 0,0:01:48.42,0:01:50.97,Default,,0000,0000,0000,,whereas the kinetic energy is\Ntrying to make the molecules
Dialogue: 0,0:01:50.97,0:01:52.38,Default,,0000,0000,0000,,go farther away from each other.
Dialogue: 0,0:01:52.38,0:01:55.77,Default,,0000,0000,0000,,And it's the balance between\Nthese two that decide
Dialogue: 0,0:01:55.77,0:01:58.05,Default,,0000,0000,0000,,what the melting and the\Nboiling points would be.
Dialogue: 0,0:01:58.05,0:02:01.05,Default,,0000,0000,0000,,So let's take a concrete\Nexample to understand that.
Dialogue: 0,0:02:01.05,0:02:02.73,Default,,0000,0000,0000,,Let's take ice at a very low temperature,
Dialogue: 0,0:02:02.73,0:02:04.83,Default,,0000,0000,0000,,say -10, -15 degrees Celsius.
Dialogue: 0,0:02:04.83,0:02:05.67,Default,,0000,0000,0000,,At this temperature, again,
Dialogue: 0,0:02:05.67,0:02:06.96,Default,,0000,0000,0000,,if we were to zoom in,
Dialogue: 0,0:02:06.96,0:02:08.43,Default,,0000,0000,0000,,we will see the atoms and molecules
Dialogue: 0,0:02:08.43,0:02:10.80,Default,,0000,0000,0000,,all stuck together due\Nto the attractive force.
Dialogue: 0,0:02:10.80,0:02:12.03,Default,,0000,0000,0000,,And they also have kinetic energy
Dialogue: 0,0:02:12.03,0:02:13.53,Default,,0000,0000,0000,,that's trying to make them go apart.
Dialogue: 0,0:02:13.53,0:02:14.64,Default,,0000,0000,0000,,However, at this temperature,
Dialogue: 0,0:02:14.64,0:02:16.65,Default,,0000,0000,0000,,it turns out the kinetic\Nenergy is very low,
Dialogue: 0,0:02:16.65,0:02:18.75,Default,,0000,0000,0000,,so low that the force of attraction
Dialogue: 0,0:02:18.75,0:02:22.08,Default,,0000,0000,0000,,actually locks them into\Nplaces giving us a solid.
Dialogue: 0,0:02:22.08,0:02:23.40,Default,,0000,0000,0000,,And the way I like to visualize this
Dialogue: 0,0:02:23.40,0:02:24.75,Default,,0000,0000,0000,,is by using some bar graph.
Dialogue: 0,0:02:24.75,0:02:26.28,Default,,0000,0000,0000,,So here's the force of attraction
Dialogue: 0,0:02:26.28,0:02:28.11,Default,,0000,0000,0000,,of the water molecules over here,
Dialogue: 0,0:02:28.11,0:02:29.97,Default,,0000,0000,0000,,and here is the kinetic energy.
Dialogue: 0,0:02:29.97,0:02:32.28,Default,,0000,0000,0000,,Look, the level of\Nkinetic energy is very low
Dialogue: 0,0:02:32.28,0:02:33.87,Default,,0000,0000,0000,,relative to the force of attraction.
Dialogue: 0,0:02:33.87,0:02:36.12,Default,,0000,0000,0000,,And as a result, you get a solid.
Dialogue: 0,0:02:36.12,0:02:37.05,Default,,0000,0000,0000,,But now comes the big question,
Dialogue: 0,0:02:37.05,0:02:39.30,Default,,0000,0000,0000,,what happens if we start heating it?
Dialogue: 0,0:02:39.30,0:02:40.44,Default,,0000,0000,0000,,Why don't you pause the video
Dialogue: 0,0:02:40.44,0:02:42.99,Default,,0000,0000,0000,,and think about what will happen\Nto the force of attraction
Dialogue: 0,0:02:42.99,0:02:44.39,Default,,0000,0000,0000,,and the kinetic energy\Nas we start heating it?
Dialogue: 0,0:02:44.39,0:02:46.86,Default,,0000,0000,0000,,Will it increase, decrease,\Nwhat happens to them?
Dialogue: 0,0:02:46.86,0:02:48.51,Default,,0000,0000,0000,,Pause and think about it.
Dialogue: 0,0:02:49.62,0:02:51.78,Default,,0000,0000,0000,,All right, what happens with\Nthe force of attraction?
Dialogue: 0,0:02:51.78,0:02:53.70,Default,,0000,0000,0000,,Nothing, because that only depends
Dialogue: 0,0:02:53.70,0:02:54.96,Default,,0000,0000,0000,,on the types of atoms and molecules.
Dialogue: 0,0:02:54.96,0:02:57.06,Default,,0000,0000,0000,,It has nothing to do with temperature.
Dialogue: 0,0:02:57.06,0:02:59.46,Default,,0000,0000,0000,,Whereas what happens with\Nthe kinetic energy, ooh, ooh!
Dialogue: 0,0:02:59.46,0:03:01.53,Default,,0000,0000,0000,,That increases with temperature,
Dialogue: 0,0:03:01.53,0:03:02.88,Default,,0000,0000,0000,,which means as we hit this up,
Dialogue: 0,0:03:02.88,0:03:04.05,Default,,0000,0000,0000,,the temperature rises
Dialogue: 0,0:03:04.05,0:03:06.75,Default,,0000,0000,0000,,and the kinetic energy\Nwill start increasing.
Dialogue: 0,0:03:06.75,0:03:08.07,Default,,0000,0000,0000,,At one particular point,
Dialogue: 0,0:03:08.07,0:03:10.83,Default,,0000,0000,0000,,the kinetic energy of these\Nparticles will be high enough
Dialogue: 0,0:03:10.83,0:03:14.01,Default,,0000,0000,0000,,that it can partially overcome\Nthe forces of attraction.
Dialogue: 0,0:03:14.01,0:03:15.63,Default,,0000,0000,0000,,And when that happens,
Dialogue: 0,0:03:15.63,0:03:17.85,Default,,0000,0000,0000,,the atoms and molecules will\Nno longer be locked in place.
Dialogue: 0,0:03:17.85,0:03:20.07,Default,,0000,0000,0000,,They will start moving around.
Dialogue: 0,0:03:20.07,0:03:23.25,Default,,0000,0000,0000,,This is when solid turns into liquid.
Dialogue: 0,0:03:23.25,0:03:28.25,Default,,0000,0000,0000,,In our case, ice starts\Nturning into liquid water.
Dialogue: 0,0:03:28.56,0:03:30.93,Default,,0000,0000,0000,,And this temperature at which it happens,
Dialogue: 0,0:03:30.93,0:03:33.99,Default,,0000,0000,0000,,for water, it happens to\Nbe about 0 degrees Celsius.
Dialogue: 0,0:03:33.99,0:03:36.00,Default,,0000,0000,0000,,And that temperature where liquid turns,
Dialogue: 0,0:03:36.00,0:03:37.44,Default,,0000,0000,0000,,sorry, solid turns into liquid,
Dialogue: 0,0:03:37.44,0:03:39.66,Default,,0000,0000,0000,,is what we call the melting point.
Dialogue: 0,0:03:39.66,0:03:43.14,Default,,0000,0000,0000,,So the melting point of\Nwater is 0 degrees Celsius.
Dialogue: 0,0:03:43.14,0:03:44.97,Default,,0000,0000,0000,,Now let's keep heating it up further.
Dialogue: 0,0:03:44.97,0:03:46.14,Default,,0000,0000,0000,,What happens as we heat it up?
Dialogue: 0,0:03:46.14,0:03:47.70,Default,,0000,0000,0000,,Again, nothing happens with\Nthe force of attraction,
Dialogue: 0,0:03:47.70,0:03:49.65,Default,,0000,0000,0000,,but the kinetic energy will keep rising.
Dialogue: 0,0:03:49.65,0:03:51.24,Default,,0000,0000,0000,,And at one particular point,
Dialogue: 0,0:03:51.24,0:03:52.29,Default,,0000,0000,0000,,it will be high enough
Dialogue: 0,0:03:52.29,0:03:55.41,Default,,0000,0000,0000,,that it can fully overcome\Nthe force of attraction.
Dialogue: 0,0:03:55.41,0:03:56.61,Default,,0000,0000,0000,,And then that happens,
Dialogue: 0,0:03:56.61,0:03:59.16,Default,,0000,0000,0000,,these molecules will now be free,
Dialogue: 0,0:03:59.16,0:04:00.99,Default,,0000,0000,0000,,almost completely free from each other,
Dialogue: 0,0:04:00.99,0:04:02.52,Default,,0000,0000,0000,,freely moving about.
Dialogue: 0,0:04:02.52,0:04:05.73,Default,,0000,0000,0000,,In other words, our liquid\Nstarts turning into gas,
Dialogue: 0,0:04:05.73,0:04:08.22,Default,,0000,0000,0000,,water starts turning into steam.
Dialogue: 0,0:04:08.22,0:04:09.63,Default,,0000,0000,0000,,So the temperature at which this happens
Dialogue: 0,0:04:09.63,0:04:11.55,Default,,0000,0000,0000,,is what we call the boiling point.
Dialogue: 0,0:04:11.55,0:04:12.93,Default,,0000,0000,0000,,And for water, that boiling point
Dialogue: 0,0:04:12.93,0:04:16.35,Default,,0000,0000,0000,,happens to be at 100 degrees Celsius.
Dialogue: 0,0:04:16.35,0:04:17.73,Default,,0000,0000,0000,,And if you further heat it,
Dialogue: 0,0:04:17.73,0:04:19.23,Default,,0000,0000,0000,,well, the steam just gets hotter,
Dialogue: 0,0:04:19.23,0:04:20.79,Default,,0000,0000,0000,,nothing else will happen.
Dialogue: 0,0:04:20.79,0:04:22.95,Default,,0000,0000,0000,,So when the kinetic energy\Nis too low to overcome
Dialogue: 0,0:04:22.95,0:04:25.62,Default,,0000,0000,0000,,any amount of attraction, we have solid.
Dialogue: 0,0:04:25.62,0:04:27.09,Default,,0000,0000,0000,,When the kinetic energy is high enough
Dialogue: 0,0:04:27.09,0:04:28.95,Default,,0000,0000,0000,,to partially overcome\Nthe force of attraction,
Dialogue: 0,0:04:28.95,0:04:29.78,Default,,0000,0000,0000,,we have liquid.
Dialogue: 0,0:04:29.78,0:04:31.38,Default,,0000,0000,0000,,And when the kinetic energy is high enough
Dialogue: 0,0:04:31.38,0:04:33.06,Default,,0000,0000,0000,,to fully overcome the force of attraction,
Dialogue: 0,0:04:33.06,0:04:34.65,Default,,0000,0000,0000,,we get a gas.
Dialogue: 0,0:04:35.76,0:04:37.38,Default,,0000,0000,0000,,All right, now let's\Nreverse the whole thing.
Dialogue: 0,0:04:37.38,0:04:39.63,Default,,0000,0000,0000,,Let's cool down our gas\Nand see what happens.
Dialogue: 0,0:04:39.63,0:04:41.25,Default,,0000,0000,0000,,Again, nothing will happen\Nto the force of attraction
Dialogue: 0,0:04:41.25,0:04:42.81,Default,,0000,0000,0000,,because it does not depend on temperature,
Dialogue: 0,0:04:42.81,0:04:44.28,Default,,0000,0000,0000,,but the kinetic energy will reduce
Dialogue: 0,0:04:44.28,0:04:47.82,Default,,0000,0000,0000,,and eventually when it goes\Nbelow the boiling point, look!
Dialogue: 0,0:04:47.82,0:04:49.92,Default,,0000,0000,0000,,It will no longer be\Nable to fully overcome
Dialogue: 0,0:04:49.92,0:04:50.82,Default,,0000,0000,0000,,the force of attraction,
Dialogue: 0,0:04:50.82,0:04:54.09,Default,,0000,0000,0000,,which means the gas will turn into liquid.
Dialogue: 0,0:04:54.09,0:04:55.77,Default,,0000,0000,0000,,We call this condensation,
Dialogue: 0,0:04:55.77,0:04:57.72,Default,,0000,0000,0000,,and this point is called\Nthe condensation point.
Dialogue: 0,0:04:57.72,0:04:59.37,Default,,0000,0000,0000,,And you can clearly see\Nthe condensation point
Dialogue: 0,0:04:59.37,0:05:01.56,Default,,0000,0000,0000,,is the same thing as the boiling point.
Dialogue: 0,0:05:01.56,0:05:03.21,Default,,0000,0000,0000,,And we've seen this before.
Dialogue: 0,0:05:03.21,0:05:05.04,Default,,0000,0000,0000,,For example, when you,\Nyou know, hold a plate
Dialogue: 0,0:05:05.04,0:05:06.39,Default,,0000,0000,0000,,over, say boiling water,
Dialogue: 0,0:05:06.39,0:05:08.70,Default,,0000,0000,0000,,we see liquid drops, that's condensation.
Dialogue: 0,0:05:08.70,0:05:10.89,Default,,0000,0000,0000,,The steam over here has temperature
Dialogue: 0,0:05:10.89,0:05:12.54,Default,,0000,0000,0000,,lower than the condensation point,
Dialogue: 0,0:05:12.54,0:05:13.68,Default,,0000,0000,0000,,lower than 100 degrees Celsius
Dialogue: 0,0:05:13.68,0:05:15.96,Default,,0000,0000,0000,,so it condenses into liquid water.
Dialogue: 0,0:05:15.96,0:05:18.18,Default,,0000,0000,0000,,And that's why you see\Nthe drops over there.
Dialogue: 0,0:05:18.18,0:05:19.08,Default,,0000,0000,0000,,Okay, and what happens
Dialogue: 0,0:05:19.08,0:05:21.54,Default,,0000,0000,0000,,if we were to reduce the\Ntemperature even more?
Dialogue: 0,0:05:21.54,0:05:24.15,Default,,0000,0000,0000,,Well, again, the kinetic\Nenergy will keep reducing.
Dialogue: 0,0:05:24.15,0:05:27.03,Default,,0000,0000,0000,,And when it's below the\Nmelting point, look!
Dialogue: 0,0:05:27.03,0:05:28.74,Default,,0000,0000,0000,,It will no longer be able to overcome
Dialogue: 0,0:05:28.74,0:05:30.48,Default,,0000,0000,0000,,any force of attraction,
Dialogue: 0,0:05:30.48,0:05:33.33,Default,,0000,0000,0000,,which means the liquid\Nwill turn back into solid.
Dialogue: 0,0:05:33.33,0:05:35.58,Default,,0000,0000,0000,,We call this the freezing point.
Dialogue: 0,0:05:35.58,0:05:36.95,Default,,0000,0000,0000,,And you can see the freezing point
Dialogue: 0,0:05:36.95,0:05:39.87,Default,,0000,0000,0000,,is the same as the melting point.
Dialogue: 0,0:05:39.87,0:05:41.84,Default,,0000,0000,0000,,And therefore, when\Nliquid water, you know,
Dialogue: 0,0:05:41.84,0:05:44.07,Default,,0000,0000,0000,,is below 0 degrees Celsius,
Dialogue: 0,0:05:44.07,0:05:46.74,Default,,0000,0000,0000,,it freezes into ice.
Dialogue: 0,0:05:46.74,0:05:48.72,Default,,0000,0000,0000,,Okay, so the key thing\Nthat we see over here
Dialogue: 0,0:05:48.72,0:05:50.79,Default,,0000,0000,0000,,is that the boiling point\Nand the melting point
Dialogue: 0,0:05:50.79,0:05:53.44,Default,,0000,0000,0000,,depends a lot on the force\Nof attraction, right?
Dialogue: 0,0:05:53.44,0:05:55.35,Default,,0000,0000,0000,,Now, here's a question:
Dialogue: 0,0:05:55.35,0:05:58.20,Default,,0000,0000,0000,,What if we consider a material like gold?
Dialogue: 0,0:05:58.20,0:05:59.91,Default,,0000,0000,0000,,Well, it turns out for gold,
Dialogue: 0,0:05:59.91,0:06:02.61,Default,,0000,0000,0000,,the force of attraction is much higher
Dialogue: 0,0:06:02.61,0:06:03.93,Default,,0000,0000,0000,,than that of water.
Dialogue: 0,0:06:03.93,0:06:04.80,Default,,0000,0000,0000,,Now, actually, the attraction
Dialogue: 0,0:06:04.80,0:06:06.48,Default,,0000,0000,0000,,is much higher in gold compared to water.
Dialogue: 0,0:06:06.48,0:06:08.76,Default,,0000,0000,0000,,So the graph should be\Nmuch higher over here.
Dialogue: 0,0:06:08.76,0:06:09.81,Default,,0000,0000,0000,,But don't worry about that.
Dialogue: 0,0:06:09.81,0:06:12.87,Default,,0000,0000,0000,,But this means now the kinetic\Nenergy needed to partially
Dialogue: 0,0:06:12.87,0:06:15.00,Default,,0000,0000,0000,,and fully overcome the force of attraction
Dialogue: 0,0:06:15.00,0:06:16.83,Default,,0000,0000,0000,,would be much higher than before.
Dialogue: 0,0:06:16.83,0:06:19.80,Default,,0000,0000,0000,,And as a result, the freezing\Npoint or the melting point
Dialogue: 0,0:06:19.80,0:06:23.28,Default,,0000,0000,0000,,and the boiling point would\Nbe much higher than before.
Dialogue: 0,0:06:23.28,0:06:26.19,Default,,0000,0000,0000,,For gold, it turns out to be, you know,
Dialogue: 0,0:06:26.19,0:06:27.63,Default,,0000,0000,0000,,about 1000 degrees Celsius
Dialogue: 0,0:06:27.63,0:06:30.27,Default,,0000,0000,0000,,and about like close to\N3000 degrees Celsius.
Dialogue: 0,0:06:30.27,0:06:32.04,Default,,0000,0000,0000,,That's why for gold,
Dialogue: 0,0:06:32.04,0:06:34.56,Default,,0000,0000,0000,,you need a much, much higher temperature
Dialogue: 0,0:06:34.56,0:06:36.30,Default,,0000,0000,0000,,for it to melt.
Dialogue: 0,0:06:36.30,0:06:37.68,Default,,0000,0000,0000,,Okay, what about nitrogen?
Dialogue: 0,0:06:37.68,0:06:38.67,Default,,0000,0000,0000,,Well, it terms for nitrogen,
Dialogue: 0,0:06:38.67,0:06:40.95,Default,,0000,0000,0000,,the force of attraction\Nis much, much lower.
Dialogue: 0,0:06:40.95,0:06:43.47,Default,,0000,0000,0000,,And therefore, the melting\Npoint and the boiling points
Dialogue: 0,0:06:43.47,0:06:44.88,Default,,0000,0000,0000,,would be much lower.
Dialogue: 0,0:06:44.88,0:06:46.28,Default,,0000,0000,0000,,And that's why it boils
Dialogue: 0,0:06:46.28,0:06:47.94,Default,,0000,0000,0000,,at a much lower temperature
Dialogue: 0,0:06:47.94,0:06:50.61,Default,,0000,0000,0000,,of -196 degrees Celsius actually.
Dialogue: 0,0:06:50.61,0:06:51.81,Default,,0000,0000,0000,,That's why at room temperature,
Dialogue: 0,0:06:51.81,0:06:53.73,Default,,0000,0000,0000,,nitrogen is a gas.
Dialogue: 0,0:06:53.73,0:06:55.56,Default,,0000,0000,0000,,So long story short,
Dialogue: 0,0:06:55.56,0:06:57.60,Default,,0000,0000,0000,,the temperature at\Nwhich the kinetic energy
Dialogue: 0,0:06:57.60,0:06:59.76,Default,,0000,0000,0000,,can partially overcome\Nthe force of attraction
Dialogue: 0,0:06:59.76,0:07:02.22,Default,,0000,0000,0000,,is what we call the melting\Nor the freezing point.
Dialogue: 0,0:07:02.22,0:07:05.10,Default,,0000,0000,0000,,That's when you have a phase\Nchange from solid to liquid
Dialogue: 0,0:07:05.10,0:07:07.20,Default,,0000,0000,0000,,or liquid to solid if\Nyou're cooling it down.
Dialogue: 0,0:07:07.20,0:07:09.27,Default,,0000,0000,0000,,And similarly, the temperature\Nat which the kinetic energy
Dialogue: 0,0:07:09.27,0:07:12.11,Default,,0000,0000,0000,,is high enough to fully overcome\Nthe force of attraction,
Dialogue: 0,0:07:12.11,0:07:14.31,Default,,0000,0000,0000,,that's what we call the boiling point.
Dialogue: 0,0:07:14.31,0:07:16.41,Default,,0000,0000,0000,,That's when you get a phase\Nchange from liquid to gas,
Dialogue: 0,0:07:16.41,0:07:19.17,Default,,0000,0000,0000,,or again, if you're cooling\Nit down, from gas to liquid.
Dialogue: 0,0:07:19.17,0:07:21.45,Default,,0000,0000,0000,,And look, since these temperatures
Dialogue: 0,0:07:21.45,0:07:23.37,Default,,0000,0000,0000,,purely depend upon how strong or weak
Dialogue: 0,0:07:23.37,0:07:26.43,Default,,0000,0000,0000,,the attractive force is and that, in turn,
Dialogue: 0,0:07:26.43,0:07:29.31,Default,,0000,0000,0000,,depends upon which types of\Nparticles we are dealing with,
Dialogue: 0,0:07:29.31,0:07:31.29,Default,,0000,0000,0000,,types of atoms and molecules\Nwe're dealing with.
Dialogue: 0,0:07:31.29,0:07:33.42,Default,,0000,0000,0000,,That's the reason why the\Nboiling points and melting points
Dialogue: 0,0:07:33.42,0:07:35.49,Default,,0000,0000,0000,,of different particles,\Ndifferent substances
Dialogue: 0,0:07:35.49,0:07:36.87,Default,,0000,0000,0000,,would be different.