2 Mg(s) + O 2 (g) → 2 MgO(s) ΔH = −1204 kJ

Hey folks, welcome back. Alright so here we're going to be identifying all of the eggs are thermic reactions that we have out of these reactions that were given now, what does exist? Thermic mean exhaust thermic means that the delta age of the reaction is going to be negative right? Because it's releasing energy, it's losing energy. If it was hypothermic then the Delta H would be positive. Now. The good thing about this problem is that we're actually given the delta ages the hopes of all of these from entropy of the reactions for all of these reactions. And we can see you know, we are given the values along with the signs. So it's very easy to tell now what would you do if you weren't given the delta H. Is of these reactions? Well for some of them you wouldn't be able to tell. But some of the other helpful, you know, signs that you could look out for our face changes for exhaust thermic exons thermic is going to be bond forming process. Okay so eggs are thermic reactions are bond forming. So delta negative DELTA H bond forming. And as far as bond forming we can take a look at the gap at the phase changes. Would that would mean going from gashes to a liquid phase to a solid phase. Right? So when we're going that way we are forming bonds. Alright, so let's take a look. So just looking at the delta age of reactions here, obviously the negative one is going to be option B than option D. And option F. So basically that's those are our answers, right? Because those are the only ones that have a negative DELTA H. But if we were to take a look at um you know using some some of the other information. Well for the first one we can see that we have a solid and then we're going to a gash to I'm sorry to Aquarius, which means basically liquid. Right? So we have a solid, we probably put it in water and it becomes a quiz. So it's it's liquid now and we're also breaking bonds here. Right? So bond forming is exhaust thermic but bond breaking is an endo thermic process. And here we are going from a solid to a liquid basically. Right? So that tells us that yes, this is endo thermic and not exhaust thermic. So if we didn't have this value, that's how we would be able to tell. Um For some of these reactions, some of the reactions is not very clear by looking at whether the bonds are forming and breaking because some reactions contain both and it's not very obvious. So we do have to look at the delta H reactions but specifically for this problem, the answers were very, very obvious here because again, of the delta H is right here that were given to us exit thermic means still to each is going to be negative. Alright folks, thank you so much for watching