00:01
Okay, this is chapter 11, section problem 70, and this is the part in the chapter where things start to get a little bit longer.
00:12
So what we have to do is calculate the amount of heat that's evolved in kilojoules for one mole of steam at 145 degrees celsius to ice at minus 50 degrees celsius, 50 degrees celsius.
00:28
And they give us the heat capacity of the steam is 2 .01 joules per gram per degree celsius and that of ice at 2 .09 jules per gram per degree celsius but that is not all the information that you even need.
00:44
You need the specific heat of steam liquid and ice and those are 2 .01, 4 .18, and 2 .09 joules per gram per degree celsius.
00:56
All respectively.
01:02
Also you need the delta h of vaporization and fusion.
01:08
Because this is the part where you have to calculate the heat that's required to this is a five -step process.
01:17
So it's the heat required to go from 145 degrees celsius of gas to 100 degrees.
01:31
And then we're going to plateau is going to convert from a gas to a liquid.
01:37
And this is fusion or condensation in our case.
01:46
And when that's all done, then it's going to be a liquid.
01:50
The temperature is going to change from 100 degrees to zero degrees until we get to the freezing point.
01:59
And then after all of the water has frozen to ice, then the ice is going to decrease from zero.
02:08
Degrees, oh, we already did that one, to what, minus 50 degrees.
02:18
And the way that this works out is this q1 plus q2 plus q3 plus q4 plus q5.
02:25
And each of these basically follows the, you know, the general formula for specific key is like q is equal to m -cat.
02:36
That's how i think of it most of the time.
02:39
So like heat required is going to equal, you know, m is mass or moles or whatever, but we'll say mass here, you know, mass times specific heat times the delta t.
02:55
Q is equal to mcat.
02:57
It's a really easy way to remember that.
02:59
But when you're going through the phase changes, well, okay, then there's no delta t, but you still just plug and chug.
03:07
And the key here is when you're doing your equations to match up the units.
03:12
So like they gave us one mole, they gave us one mole esteem.
03:17
So, you know, when i was doing my math, well, i noticed that these are in grams.
03:24
So you have to go from grams to moles every time, right? you know, you know, or moles to gram.
03:32
There's one mole.
03:34
There's, you know, 18 grams of water per one mole, you know, and you keep going on and so forth.
03:41
But this is the part where you got to add these all up individually, and i can go through those right now.
03:52
Okay.
03:52
So the first one that we got to do.
03:53
Like i said, is going from the hot gas to a little bit of a colder gas.
03:59
So we started off with one mole of steam, and then if we can change that into grams of steam, by multiplying by the molecular rate, 18 grams from mole...