so these are spontaneous physical processes but they happen to be endothermic all right so this is going against my tent we said that endothermic reactions tend to be spontaneous or tend to be non spontaneous rather well here are three examples all right so here are three examples of spontaneous and no thermic reactions so they're requiring energy but they still go all right so what do they have in common well let's try to break down what these processes are so melting of ice what's that mean what's going on well just think about what's going on physically with the molecules aren't all right an equation okay so ice is what water right so I want to write down what water yeah that's what I'm looking for so solid water is turning into liquid water right that's what we mean by melting and we know this happens you pull ice cubes out of your freezer they're gonna melt so that's spontaneous right they're gonna happen you don't have to do anything to it it's gonna happen well I mean it's temperature dependent so it doesn't happen till above zero Celsius but it does happen all right what's going on with the evaporation of liquid water going from a liquid to a gas this time so water the liquid phase is going to water in the gas phase and that happens too right so if I spilled some water accidentally on this desk all right we came in tomorrow that water probably wouldn't be there right so the dissolution of sodium chloride in water so what's going on there so dissolutions are we mean dissolving right it's all two aqueous that's what's going on so we get sodium chloride is going in to dissociating dissolving to sodium and chloride alright so what do these three processes have in common they're all face changes that's you know they're just physical changes official changes and that's what's going on it turns out that once we start to look at these all three of these processes are getting more disordered or they're less ordered you can say it either way less ordered or more disordered all three processes are getting more disordered or less ordered all right and so if we think about this you know physically what's going on you know in the water solid all those water molecules are trapped and you know crystal so they're all sitting next to each other there's your ice cube all right and then they melt and suddenly they're just you know spilled out on the desk and they get to move around and the salt phase are all locked into position yeah doing the solid dance okay again at the same time one phenomenon all right and then once they mount they get to do the liquid dance okay still got it still got it all right so yeah they get there they're a lot more disordered okay you can you can tell where water molecule is going to be in the crystal phase and the solid there you just don't know where they're gonna be at in liquid phase alright what's going on in the evaporation well you got lit water in the liquid phase and they get to do the liquid dance okay they're doing liquid dance but they're always to each other always incan in contact with each other because those hydrogen bonds right then they evaporate suddenly they're flying around and there's lots of space in between them and so if you just look at these pictures like which ones look more ordered obviously the solid looks a lot more ordered than the liquid phase the liquid phase looks a lot more ordered than the gas phase and so we see they're getting less ordered more disordered and then again one more time with the sodium chloride they're in the solid phase and then dissolve them in water some of their aqueous ions get to swim around yes you're absolutely right good catch I did that on purpose to make sure everyone was paying attention good job are you yes that isn't this all face that's what the equation should write thank you so again we're going from a much more ordered system sodium chloride crystals suddenly they're equally science swimming around there's much more disordered and it turns out that this is what nature tends to do as well okay in terms of energy nature tends to go downhill from high potential energy to low potential energy another thing nature tends to do is become more too