0:02 so what we're really interested in
0:05 chemistry is using thermochemistry and
0:07 measuring the kind of heat that it gets
0:09 transferred in our different kinds of
0:12 reactions or physical propert Pro
0:14 processes so we can have a couple of
0:17 definitions of things we want to study
0:20 so our system is what we want to study
0:29 else so we can look at our different
0:31 kind of systems we can first think about
0:34 our exothermic system and our exothermic
0:36 process so if we have a system that
0:38 we're studying which releases heat what
0:42 we're going to see in here is our heat
0:45 is going to go leave our system and go
0:48 into the surroundings of whatever is
0:50 there so you'll have lots of heat that
0:53 leaves out and we have some sort of cue
0:55 that's in there and what we can do is we
0:58 can measure the cue of our surroundings
1:01 for that exothermic process so after a
1:03 while what happens with an exothermic
1:05 process we're going to start out with a
1:07 certain temperature and as everything
1:10 gets uh re-equilibrated after the
1:13 reaction we should see the temperature
1:16 increase for an exothermic reaction and
1:18 the opposite thing happens for an
1:20 endothermic system so if we have some
1:23 sort of endothermic system heat from the
1:26 C surroundings are going to have to go
1:28 into the
1:30 system so this is really cool we'll
1:33 start off with a certain temperature and
1:35 after the reaction is done and it's kind
1:38 of equal out you we should see that the
1:41 temperature should actually drop for the
1:43 entire uh
1:46 calorimeter so this is a really good way
1:49 of measuring these kinds of reactions so
1:51 let me go ahead and show you two
1:55 different kinds of calorimeters that are
1:59 common in in the chemistry lab uh and
2:01 the first one looks really simple but it
2:04 is astoundingly precise in terms of its
2:07 measurements and this is what we call a coffee
2:08 coffee cup
2:10 cup
2:13 calorimeter and what we usually have is
2:15 some sort of Styrofoam cups you usually
2:17 have two of them and those act as
2:20 insulators so that we can isolate what
2:22 we're trying to study to inside of the
2:24 coffee cup and we put in there a
2:26 thermometer which measures the
2:28 temperature and we have some sort of
2:31 stir on it and we put a lid on it so
2:34 that heat doesn't leave the system and
2:37 so we can do a reaction that's inside of
2:39 the coffee cup and we can measure the
2:41 change in temperature based on the
2:44 thermometer of this reaction and it
2:46 works really well for a lot of the
2:49 different kinds of activities so we
2:50 typically put water in there we can
2:54 measure the temperature before and after
2:57 uh we do our activity and be able to
3:01 measure our um Heat or heat that's being
3:04 transferred another type of
3:08 calorimeter is what we call a a bomb
3:10 calorimeter and what a bomb calorimeter
3:13 does it keeps our volume very constant
3:15 so in the previous this is actually what
3:20 we call um a a uh we keep our pressure
3:22 uh constant so this is at constant
3:25 pressure in a bomb calorimeter we keep
3:28 this at constant volume so we actually
3:31 seal our reaction in inside of our bombb
3:33 calorimeter uh in here so we can have
3:36 this inner vessel that's inside we can
3:39 actually do a reaction in there that
3:41 doesn't um that can't see any kind of
3:45 water so then the cue of this what
3:49 happens inside of here goes into another
3:53 outer vessel that has um a liquid in
3:56 there so inside that liquid can actually
4:00 absorb and or release kind of um heat to
4:04 it and then the whole calorimeter will
4:07 have a a um a heat capacity to it so
4:10 whenever you see a bomb calorimeter you
4:13 will typically see a heat capacity for
4:15 the bomb
4:18 itself so we can differentiate between
4:21 the two different reactions but actually
4:23 the calculations for these aren't that
4:26 different between the two we can go
4:28 ahead and follow the law of conservation
4:30 of energy for both both of these kinds
4:34 of systems and uh how you navigate these
4:36 kinds of process is first realizing you
4:38 have to do some sort of calorimetry and
4:41 the main concept that comes out is this
4:44 law conservation energy and this law
4:48 conservation energy says we can't
4:53 create um energy we can only
4:56 transfer it so we have to read our
4:59 problems very carefully and look for all
5:01 the cues
5:04 so what kinds of cues are relevant to it
5:08 to that problem and the sum of all those
5:11 cues based on the conservation energy equals
5:13 equals
5:16 zero and so this gives us the kind of
5:19 concept that our Q of our
5:22 system which is what we're trying to
5:24 study and our Q of the
5:27 surroundings which is everything that's
5:29 not what we're studying has to equal zero
5:30 zero
5:34 so you will see this as Q of the
5:38 system equals Q of the surroundings but
5:40 what gets crazy in kind of thinking
5:42 about problems sometimes our
5:45 surroundings or our queue of the system
5:48 has multiple cues in there so I always
5:50 like to kind of think about it this way
5:53 and just take all of our cues and sum
5:55 them up and make them all equal to zero
5:57 because there's usually one thing in
5:59 there you're trying to study and you're
