 So, let's finish up the day doing one of these bond association energy problems. So this one in particular says, use the data in the table given to calculate an approximate heat of the reaction in kilojoules per mole for the industrial synthesis of ethanol from ethylene. Okay? So, this is ethylene, this is ethanol. They gave you the molecular formulas of all of this stuff, but I wrote it out for you so we can actually see which bonds are being broken here. Okay? So just remember Hess's Law. So it's the products minus the reactions, right? So in this case we get bond association energies, and I've listed the bonds that are shown here. Let's just add up all these bonds. So in the reactants we have one, two, three, four CH bonds. Do you guys see that? So CH, we've got four of them. So we've got C, C double bond, one of them, and two OH bonds. Is everybody okay with that? In the products we have one, two, three, four, five CH bonds. Like that. C, C bond, one CO bond, and one OH bond. Is everybody okay with that? So now what do we do? Well we just use Hess's Law like we did before. Okay? So I'm going to rely on you guys because I'm going to have to erase this part. Okay? So Hess helped me out. So do you guys have all this bottom part written out? So we're going to try to figure out what is the standard heat of this reaction. So remember we've got to figure out the bond energy, the total bond energy of the products, and subtract that from the total bond energy of the reactants. So what do we say? One, two, three, four, five CHs. So five times four to ten kilojoules per mole. Does that make sense? See which one this one? Okay, three fifty. Sorry, I just didn't hear what you said. And then you said the CO. We want to do the CO next. Okay, so how many of those do we have? Just the one. So that's three fifty as well. Do we have any other bonds in there? One oh eight. Yup, the one oh eight. So that's going to be four sixty and no more, right? And so then we're going to do what? Subtract that or subtract the products from that or the reactants from that. So in the reactants what do we have? One, two, three, four CH bonds. So four times four to ten. We're going to add that to one CC bond. And that's it. Everybody okay with that? So this is how to use Essence Law during bond association energy to figure out the heat of the reaction. So now let's just go ahead. Oh, we need to do the OHS2, sorry. Good call. Plus the two four sixes. If I did this right, I'd get a number of negative seventy eight.