0:00
Hello everyone.
00:01
Today we're doing problem 6 .32, and this problem asks us to identify the delta h for each reaction.
00:09
So remember, your delta h for a reaction equals the sum of delta h of your reactants minus the sum of delta h of your products.
00:20
So another way to say this is your delta h, so let me write it out.
00:24
So your delta h of reaction equals the sum of delta h of reactants minus the sum of delta h of products so another way of saying this is the delta h of your reaction equals the sum of the delta h of the bonds being broken minus the sum of the delta h of bonds being formed.
01:02
So these are synonymous.
01:04
You can say it either way, reactants minus products.
01:07
You're breaking your reactants bond in order to form the products bond.
01:11
So there's two different ways to say this.
01:12
So now using that, let's form our using the table.
01:17
Let's determine the delta h of our reactants.
01:20
So here we're seeing that we have ethane.
01:23
We're taking away one of these hydrogens and replacing it for one bromine.
01:27
So we know that one carbon hydrogen bond is breaking, and we also know that one br br bond is breaking.
01:35
So the energy of these is equal to 410 kilojoules per mole, and the diatomic bromide breaking is 192 kilojoules per mole.
01:47
So that gives us a total bond breaking, because remember, we're only breaking one of these carbon hydrogen bonds, and we're breaking this bromin bromin bond in order to form this carbon bromine bond.
01:58
And its hydrogen bromine bond.
02:01
So this equals to a total of positive 602 kilojoules per mole.
02:06
Now our products, we're now forming a carbon bromine bond.
02:17
So we're now forming a carbon bromine bond.
02:23
Specifically, we're forming that on an ethene scaffold, and we're also forming an hbr bond.
02:30
This equals an energy of 285 kilojoules per more, and hbr bond formation generates 668, 368 kilojoules of mole.
02:47
So the total of that equals 653 kilojoules per mole.
02:59
But remember, you're subtracting the bonds being formed.
03:04
So we'll put a minus sign here.
03:06
So if we just take these, 602 minus 653, we get a total delta g over your delta h over your reaction being minus 51 kilojoule per mole so that means that's a negative number so this reaction is exothermic meaning that your products are favored over the reactants products being lower energy more stable and higher in abundance than your starting material and your kq in this equation is going to be greater than one next problem we have this hydroxide radical methane gas and you see here that we're breaking one bond of our methane and we're donating it to our oh radical.
03:53
So the bond that we're breaking in our study material is one bond in our methane.
03:59
So a carbon hydrogen bond, which forms 435 kilojoules of energy.
04:10
Remember, this is for methane.
04:12
And we're not breaking any bonds in this radical, actually.
04:15
So this is the only bond that we're breaking.
04:17
And what are we forming? well, actually, we're forming two bonds.
04:21
Number one is we are forming our h2o bonds, so one h -o bond.
04:31
That's 498 kilojoules per mole...