00:01
So in this problem we have, let's see here, we want to calculate the air versibility of the process described in problem 41.
00:12
And that was we're burning carbon with pure oxygen in a constant volume process.
00:19
Let's see here.
00:20
Let me actually go back and look at exactly what problem 41 says.
00:25
So we get that clear.
00:28
Okay, let's see, 41.
00:30
A rigid vessel contains 2 kilomoles of, carbon and two kilomoles of oxygen.
00:37
So we know how much we have and the combustion occurs and the resulting product consists of one kilo -mole of carbon dioxide, one kilo -mole of carbon monoxide and half a kilo -mole of oxygen.
00:52
And so in problem 41 we wanted to determine the final pressure in the vessel and the heat transfer from the vessel during the process.
01:00
In this case we are just we want to figure out the irreversibility.
01:11
So again, it's calculating these irreversibilities is just kind of a lot of looking stuff up and for these chemical reactions.
01:19
Anyway, again, it's just a lot of looking stuff up.
01:23
So we know in the reactants, we have two kilomoles of gas and in the products, it's all gas.
01:36
So we have 2 .5 kilomoles of gas.
01:37
So we have 2 .5 kilomoles of gas.
01:39
We can see here that in fact, you know, we didn't get complete combustion here because we have some co2 and some oxygen left over.
01:51
So we then we can figure out the pressure in the products because we need to, well, we need that we need that, i'll just say, because we know that this is the internal energy because it's a constant volume process, there's no flows.
02:07
So we're going to need the pressure in the products.
02:09
That's the pressure in the reactants, which was 200 kilopascals, times the ratio of the number of moles of products to reactants, times the ratio of the temperature of the products to the reactants.
02:23
Again, the reactants, the products, temperature of the products was given as 1 ,000 calvin.
02:34
And this was given too in the 41.
02:36
So then we calculate that the pressure of the products, or after the combustion happens is 838 kilopascals.
02:46
So obviously we pressurize this.
02:50
Now, the enthalpy in the reactants, these were all at reference conditions.
02:59
And let's see here, the entropy of formation of these are both zero.
03:04
So the total enthalpy in the reactants is zero.
03:08
Let's see here.
03:09
In the products, we have enthalpy of formation of the co2, plus the change as we go up to this temperature and pressure.
03:19
And then the enthalpyal formation of the co plus the change as we go from the reference to the actual.
03:27
And then the enthalpyal formation of the oxygen with the zero plus the change.
03:32
And that all adds up to minus 438 megajoules...