[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:01.18,0:00:03.90,Default,,0000,0000,0000,,- [Instructor] Let's imagine a reaction
Dialogue: 0,0:00:03.90,0:00:05.40,Default,,0000,0000,0000,,that is in equilibrium.
Dialogue: 0,0:00:05.40,0:00:10.40,Default,,0000,0000,0000,,So A plus B, they can\Nreact to form C plus D,
Dialogue: 0,0:00:10.53,0:00:11.85,Default,,0000,0000,0000,,or you could go the other way around.
Dialogue: 0,0:00:11.85,0:00:15.39,Default,,0000,0000,0000,,C plus D could react to form A plus B.
Dialogue: 0,0:00:15.39,0:00:17.67,Default,,0000,0000,0000,,And we assume that\Nthey've all been hanging
Dialogue: 0,0:00:17.67,0:00:20.49,Default,,0000,0000,0000,,around long enough for\Nthis to be in equilibrium
Dialogue: 0,0:00:20.49,0:00:24.06,Default,,0000,0000,0000,,so that the reaction that goes\Nfrom A plus B to C plus D,
Dialogue: 0,0:00:24.06,0:00:25.53,Default,,0000,0000,0000,,it's happening at the same rate
Dialogue: 0,0:00:25.53,0:00:29.79,Default,,0000,0000,0000,,as the reaction from C plus D to A plus B.
Dialogue: 0,0:00:29.79,0:00:31.80,Default,,0000,0000,0000,,Now what we're gonna do is imagine
Dialogue: 0,0:00:31.80,0:00:35.52,Default,,0000,0000,0000,,what would happen if we\Ndisturb this equilibrium,
Dialogue: 0,0:00:35.52,0:00:37.98,Default,,0000,0000,0000,,and let's say we disturb this equilibrium
Dialogue: 0,0:00:37.98,0:00:42.96,Default,,0000,0000,0000,,by taking some C and D out of,
Dialogue: 0,0:00:42.96,0:00:45.21,Default,,0000,0000,0000,,let's say this was a\Nsolution of some kind.
Dialogue: 0,0:00:45.21,0:00:50.19,Default,,0000,0000,0000,,So I just one time reduced\Nthe concentration of C and D.
Dialogue: 0,0:00:50.19,0:00:51.90,Default,,0000,0000,0000,,Well, that disturbance, first of all,
Dialogue: 0,0:00:51.90,0:00:54.30,Default,,0000,0000,0000,,is going to throw us out of equilibrium,
Dialogue: 0,0:00:54.30,0:00:57.00,Default,,0000,0000,0000,,because now the reaction\Nthat goes from C plus D
Dialogue: 0,0:00:57.00,0:01:00.06,Default,,0000,0000,0000,,to A plus B isn't going to\Nbe able to happen as often.
Dialogue: 0,0:01:00.06,0:01:01.74,Default,,0000,0000,0000,,'Cause I just took C and D out,
Dialogue: 0,0:01:01.74,0:01:04.08,Default,,0000,0000,0000,,they're not going to bump\Ninto each other enough
Dialogue: 0,0:01:04.08,0:01:07.47,Default,,0000,0000,0000,,to now form A and B at the same rate.
Dialogue: 0,0:01:07.47,0:01:09.87,Default,,0000,0000,0000,,So if you think about the net direction
Dialogue: 0,0:01:09.87,0:01:11.79,Default,,0000,0000,0000,,until we hit a new equilibrium,
Dialogue: 0,0:01:11.79,0:01:13.62,Default,,0000,0000,0000,,this is going to happen less.
Dialogue: 0,0:01:13.62,0:01:15.30,Default,,0000,0000,0000,,and this, initially, is going
Dialogue: 0,0:01:15.30,0:01:16.92,Default,,0000,0000,0000,,to be happening at the same amount.
Dialogue: 0,0:01:16.92,0:01:19.95,Default,,0000,0000,0000,,So you're going to have a net direction
Dialogue: 0,0:01:19.95,0:01:22.02,Default,,0000,0000,0000,,until we hit equilibrium again
Dialogue: 0,0:01:22.02,0:01:26.04,Default,,0000,0000,0000,,that goes from A plus B to C plus D.
Dialogue: 0,0:01:26.04,0:01:27.24,Default,,0000,0000,0000,,And then if you wait long enough,
Dialogue: 0,0:01:27.24,0:01:29.94,Default,,0000,0000,0000,,you're going to hit\Nback at an equilibrium.
Dialogue: 0,0:01:29.94,0:01:31.83,Default,,0000,0000,0000,,Now, let's think about what just happened.
Dialogue: 0,0:01:31.83,0:01:35.40,Default,,0000,0000,0000,,We disturbed the equilibrium\Nby taking C and D out.
Dialogue: 0,0:01:35.40,0:01:37.50,Default,,0000,0000,0000,,Until we hit our new equilibrium,
Dialogue: 0,0:01:37.50,0:01:41.01,Default,,0000,0000,0000,,we have more of the\Nreaction going from A plus B
Dialogue: 0,0:01:41.01,0:01:43.50,Default,,0000,0000,0000,,to C plus D on a net basis.
Dialogue: 0,0:01:43.50,0:01:44.79,Default,,0000,0000,0000,,And so it's relieving it.
Dialogue: 0,0:01:44.79,0:01:48.54,Default,,0000,0000,0000,,It's relieving the fact that\Nwe took some C plus D out.
Dialogue: 0,0:01:48.54,0:01:51.84,Default,,0000,0000,0000,,And it's going to reestablish\Na new equilibrium.
Dialogue: 0,0:01:51.84,0:01:54.72,Default,,0000,0000,0000,,If we took A plus B out, or A and B out,
Dialogue: 0,0:01:54.72,0:01:57.42,Default,,0000,0000,0000,,or even just one of them, A or B out,
Dialogue: 0,0:01:57.42,0:01:59.43,Default,,0000,0000,0000,,then you would have the opposite happen.
Dialogue: 0,0:01:59.43,0:02:01.56,Default,,0000,0000,0000,,But either way, if you disturb it,
Dialogue: 0,0:02:01.56,0:02:04.35,Default,,0000,0000,0000,,the system shifts to\Nrelieve the disturbance
Dialogue: 0,0:02:04.35,0:02:06.57,Default,,0000,0000,0000,,and re-establish equilibrium.
Dialogue: 0,0:02:06.57,0:02:08.64,Default,,0000,0000,0000,,Now this principle, you might imagine,
Dialogue: 0,0:02:08.64,0:02:10.44,Default,,0000,0000,0000,,'cause it's been sitting\Nhere the whole time,
Dialogue: 0,0:02:10.44,0:02:14.49,Default,,0000,0000,0000,,is Le Chatelier's Principle\Nthat describes that.
Dialogue: 0,0:02:14.49,0:02:17.52,Default,,0000,0000,0000,,And it's not just by\Ndisturbing it by changing,
Dialogue: 0,0:02:17.52,0:02:21.18,Default,,0000,0000,0000,,say, concentrations of\Nreactants or products.
Dialogue: 0,0:02:21.18,0:02:23.01,Default,,0000,0000,0000,,You could be changing other things.
Dialogue: 0,0:02:23.01,0:02:27.33,Default,,0000,0000,0000,,So for example, let's imagine\Nthe reversible reaction,
Dialogue: 0,0:02:27.33,0:02:31.35,Default,,0000,0000,0000,,let's say A plus B, and let's\Nsay these are all gases.
Dialogue: 0,0:02:31.35,0:02:34.65,Default,,0000,0000,0000,,So A plus B can react to form C,
Dialogue: 0,0:02:34.65,0:02:37.26,Default,,0000,0000,0000,,or C could react to,
Dialogue: 0,0:02:37.26,0:02:40.05,Default,,0000,0000,0000,,I guess you could imagine,\Nbreak up into A plus B.
Dialogue: 0,0:02:40.05,0:02:42.51,Default,,0000,0000,0000,,And let's imagine that\Nthese are all gases.
Dialogue: 0,0:02:43.47,0:02:45.00,Default,,0000,0000,0000,,So let's assume that it's happening
Dialogue: 0,0:02:45.00,0:02:47.67,Default,,0000,0000,0000,,in a container of a certain size.
Dialogue: 0,0:02:47.67,0:02:50.58,Default,,0000,0000,0000,,And let's say that I were to shrink
Dialogue: 0,0:02:50.58,0:02:52.92,Default,,0000,0000,0000,,the volume of that container.
Dialogue: 0,0:02:52.92,0:02:56.16,Default,,0000,0000,0000,,What do you think is going\Nto happen in that situation?
Dialogue: 0,0:02:56.16,0:02:59.88,Default,,0000,0000,0000,,Well, if I shrink the\Nvolume of that container,
Dialogue: 0,0:02:59.88,0:03:02.37,Default,,0000,0000,0000,,then you have a situation where A and B
Dialogue: 0,0:03:02.37,0:03:04.14,Default,,0000,0000,0000,,are going to bump into each other more.
Dialogue: 0,0:03:04.14,0:03:06.54,Default,,0000,0000,0000,,They're going to collide\Ninto each other more.
Dialogue: 0,0:03:06.54,0:03:11.54,Default,,0000,0000,0000,,And so you are going to have a\Nnet direction go in that one.
Dialogue: 0,0:03:11.58,0:03:16.58,Default,,0000,0000,0000,,You'll still have some C reacting\Nto break up into A and B,
Dialogue: 0,0:03:16.65,0:03:19.23,Default,,0000,0000,0000,,but you're going to have\Nmore A and B reacting,
Dialogue: 0,0:03:19.23,0:03:21.81,Default,,0000,0000,0000,,bumping into each other,\Ncolliding each other to form C,
Dialogue: 0,0:03:21.81,0:03:24.24,Default,,0000,0000,0000,,until we hit a new equilibrium.
Dialogue: 0,0:03:24.24,0:03:26.88,Default,,0000,0000,0000,,And notice what is happening there.
Dialogue: 0,0:03:26.88,0:03:30.06,Default,,0000,0000,0000,,When A plus B reacts to form C,
Dialogue: 0,0:03:30.06,0:03:33.15,Default,,0000,0000,0000,,it decreases the number of\Nparticles in the container
Dialogue: 0,0:03:33.15,0:03:35.76,Default,,0000,0000,0000,,and it decreases the pressure.
Dialogue: 0,0:03:35.76,0:03:39.81,Default,,0000,0000,0000,,And so, eventually you're\Ngoing to hit a new equilibrium.
Dialogue: 0,0:03:39.81,0:03:41.76,Default,,0000,0000,0000,,But when you disturb that equilibrium
Dialogue: 0,0:03:41.76,0:03:43.47,Default,,0000,0000,0000,,by changing the volume,
Dialogue: 0,0:03:43.47,0:03:46.74,Default,,0000,0000,0000,,the system shifted to\Nrelieve that disturbance.
Dialogue: 0,0:03:46.74,0:03:49.86,Default,,0000,0000,0000,,In that case, the disturbance\Nwas an increased pressure
Dialogue: 0,0:03:49.86,0:03:52.23,Default,,0000,0000,0000,,and it reestablished the equilibrium.
Dialogue: 0,0:03:53.07,0:03:55.11,Default,,0000,0000,0000,,Let's imagine another reaction.
Dialogue: 0,0:03:55.11,0:03:58.59,Default,,0000,0000,0000,,Let's imagine A plus B.
Dialogue: 0,0:03:58.59,0:04:00.84,Default,,0000,0000,0000,,And let's say this is\Nan endothermic reaction.
Dialogue: 0,0:04:00.84,0:04:04.83,Default,,0000,0000,0000,,So I'm gonna treat energy\Nreally as a reactant here.
Dialogue: 0,0:04:04.83,0:04:07.32,Default,,0000,0000,0000,,Just to make it clear that\Nthis is an endothermic reaction
Dialogue: 0,0:04:07.32,0:04:10.47,Default,,0000,0000,0000,,that could form C plus D.
Dialogue: 0,0:04:10.47,0:04:13.71,Default,,0000,0000,0000,,Or you could have C plus D react
Dialogue: 0,0:04:13.71,0:04:15.75,Default,,0000,0000,0000,,to form A plus B plus energy.
Dialogue: 0,0:04:15.75,0:04:18.18,Default,,0000,0000,0000,,So the reaction that starts with C plus D
Dialogue: 0,0:04:18.18,0:04:20.37,Default,,0000,0000,0000,,and forms A plus B in energy,
Dialogue: 0,0:04:20.37,0:04:23.01,Default,,0000,0000,0000,,well, that's going to be exothermic.
Dialogue: 0,0:04:23.01,0:04:25.80,Default,,0000,0000,0000,,So let's imagine what would happen here,
Dialogue: 0,0:04:25.80,0:04:27.90,Default,,0000,0000,0000,,and let's imagine it's at equilibrium,
Dialogue: 0,0:04:27.90,0:04:30.18,Default,,0000,0000,0000,,but then we disturb that equilibrium.
Dialogue: 0,0:04:30.18,0:04:32.61,Default,,0000,0000,0000,,What happens if we\Ndisturb that equilibrium
Dialogue: 0,0:04:32.61,0:04:36.57,Default,,0000,0000,0000,,by adding more energy over here?
Dialogue: 0,0:04:36.57,0:04:38.84,Default,,0000,0000,0000,,Well, if I add more energy,
Dialogue: 0,0:04:38.84,0:04:40.41,Default,,0000,0000,0000,,it's going to be easier
Dialogue: 0,0:04:40.41,0:04:43.71,Default,,0000,0000,0000,,for this endothermic reaction to occur,
Dialogue: 0,0:04:43.71,0:04:46.11,Default,,0000,0000,0000,,and so it's going to\Ndisturb the equilibrium
Dialogue: 0,0:04:46.11,0:04:49.14,Default,,0000,0000,0000,,in that direction right over there.
Dialogue: 0,0:04:49.14,0:04:53.37,Default,,0000,0000,0000,,And so you're going to have\Nthat energy really get used up
Dialogue: 0,0:04:53.37,0:04:55.59,Default,,0000,0000,0000,,to form more C and D.
Dialogue: 0,0:04:55.59,0:04:57.57,Default,,0000,0000,0000,,You could imagine the other way.
Dialogue: 0,0:04:57.57,0:05:00.66,Default,,0000,0000,0000,,What happens if I were\Nto take energy away?
Dialogue: 0,0:05:00.66,0:05:05.66,Default,,0000,0000,0000,,Well, you need energy for A and\NB to react to form C plus D.
Dialogue: 0,0:05:05.70,0:05:08.04,Default,,0000,0000,0000,,So if you were to take energy away,
Dialogue: 0,0:05:08.04,0:05:10.86,Default,,0000,0000,0000,,then the reaction that starts with A and B
Dialogue: 0,0:05:10.86,0:05:12.60,Default,,0000,0000,0000,,is going to happen less.
Dialogue: 0,0:05:12.60,0:05:15.18,Default,,0000,0000,0000,,And so you're gonna have a net direction
Dialogue: 0,0:05:15.18,0:05:19.11,Default,,0000,0000,0000,,with C plus D reacting to form A plus B
Dialogue: 0,0:05:19.11,0:05:21.54,Default,,0000,0000,0000,,until you hit a new equilibrium.
Dialogue: 0,0:05:21.54,0:05:23.43,Default,,0000,0000,0000,,But the important thing to realize here
Dialogue: 0,0:05:23.43,0:05:25.05,Default,,0000,0000,0000,,is in every situation,
Dialogue: 0,0:05:25.05,0:05:26.70,Default,,0000,0000,0000,,whether we're disturbing the equilibrium
Dialogue: 0,0:05:26.70,0:05:29.55,Default,,0000,0000,0000,,by changing concentration,\Nby changing volume,
Dialogue: 0,0:05:29.55,0:05:31.38,Default,,0000,0000,0000,,and therefore changing pressure,
Dialogue: 0,0:05:31.38,0:05:33.75,Default,,0000,0000,0000,,or you're adding or taking away energy,
Dialogue: 0,0:05:33.75,0:05:36.30,Default,,0000,0000,0000,,which you could do in the form\Nof changing the temperature,
Dialogue: 0,0:05:36.30,0:05:39.90,Default,,0000,0000,0000,,the system shifts to\Nrelieve that disturbance
Dialogue: 0,0:05:39.90,0:05:42.51,Default,,0000,0000,0000,,and re-establish a new equilibrium,
Dialogue: 0,0:05:42.51,0:05:45.30,Default,,0000,0000,0000,,which, once again, is Le\NChatelier's Principle.