so the two examples for catalysis that we are going to talk about the first one is a catalytic converter okay so in every car and automobile nowadays our catalytic converters okay so what they do is they use some type of catalyst catalytic to convert usually pollutants into less much less harmful stuff so like nitrogen monoxide carbon monoxide those are pollutants very toxic produces convert those to nitrogen and carbon dioxide that's a fuel fragment okay so unburnt gasoline that doesn't go for a lot of times we'll hear a complete combustion you know some type of hydrocarbon plus oxygen goes to co2 water that's called complete combustion of course in real life we don't always have complete combustion of incomplete combustion so you've fuel fragments and that leads to again a bigger problem like the 70s and 80s was smog so we're out what the catalyst is and how it's going to stabilize the reactive intermediates and we're going to do it by watching the movie all right so what happens is that platinum okay so let's say that's platinum metal alright and that oxygen atom sitting there binding to that it's absorbing it just sitting on top is stabilized by the electrons in those platinum atoms okay so that oxygen atom really wants two more electrons to get to the octet rule right and normally that's why it reacts with everything and why it's gonna be O two but the Platinum's electrons stabilize that oxygen atom so that it can sit there and be by itself okay so oxygen is just sitting on top of it it's kind of like fueling those electrons for those bags and stabilized until something else comes along and oxygen combines with like another oxygen add two of those single oxygen atoms find each other they'll share two pairs of electrons form that double bond suddenly it's an oxygen molecule much more stable and it leaves okay so that's how the candidate converters stabilize those reactive intermediates okay that oxygen that normally wouldn't exist can sit there for while until something comes along too reactive yes yeah so it's not a really chemical bond so it's not forming a ball of platinum but it is getting close enough that those electrons can't stabilize it yeah they wouldn't share or release I don't think so I don't think so and so climb them stable enough that it's not going to give up the floor that is a good question whether orbitals overlap in I don't know okay but it does tell us why we have to use such expensive metals like platinum plating okay if that was any other metal like it would oxidize the oxygen would just take those two electrons bo2 - it's a nickel or iron or anything like that oxygen which is reactive away well platinum is really stable not going to give up its electrons very easily not even to an oxygen atom oxygen atom can sit there platinum safe until not something else comes with reacts away that oxygen yes yeah generally platinum and palladium and rhodium are very very stable and they're they're often sometimes you'll hear them called noble metals like noble gases these are showing reactive and there are some of the only metals that you find naturally occurring in nature naturally occurring in nature that's those are words okay that you'll find them as they're pure substance like you can mine gold and silver and platinum palladium every other metals with minerals okay so it's you know iron oxide some type of compound that's of course why they're used for things like jewelry all right so that's one way I catalyst can stabilize a high potential energy transition state and that's where the calloc converters the other example that your book talks about and we'll talk about slightly different mechanism but a really important class of catalysts are enzymes okay so an enzyme okay which you probably are it down here I'll part right here is a protein that catalyzes biological reactions or biochemical reactions and turns out to be a really important class of biological molecules and time to do a lot of work in your body okay there are involved in pretty much I don't almost every you know phase of you know biological system they're involved with metabolism breaking down molecules they're involved in building up molecules building DNA building proteins themselves and so how an enzyme usually works is the substrate which is the reactant binds to the enzyme active site so it's a really similar case that oxygen binding to the metals where those other molecule binding to the metals in the collect convert the substrate they're active molecules by to watch the Civic area I guess unlike the metals they do find to one specific area called the active site and then they form a complex so again they're not really a true chemical bond we're starting just binding there usually through intermolecular forces not usually always do intermolecular forces which I usually use as an example why you never like horses you know something we talked about in Gen chem one are very important so the two models for enzyme substrate complexes or enzyme active sites that you might learn in a biology class there is the locking key model okay where the substrate fits exactly into the active site and like a key into a lock it's a perfect fit and that's what fits in that active site and so that's what gets you know catalyzed by the enzyme the other models called the induced fit model where the protein enzyme and or or the substrate kind of changed shape so that they fit together so as the substrate gets closer to the active site though enzyme will change shape a little bit so that's a perfect fit and that's all triggered by in like a force it's like hydrogen bonding dipole-dipole forces all that kind of stuff right but anyways then the reaction happens and it happens in a much faster rate because it's being catalyzed okay so here's a one good example okay so if you eat sucrose okay um you know drinking a soda or coffee tea your sugar and your same bath sugar in your drinks okay right now okay so sugar lots of drinks yeah cute coffee or some sodas and things like that it turns out that our body uses water to break down sucrose so sucrose or the disaccharide says two monosaccharides glucose and fructose of course we want to use glucose for our southern respiration we use fructose as well well we want to break that down one breakdown of sucrose and we actually most of time if we're going to metabolize a carbohydrate or a bigger molecule or a lipid we break it down by using water okay so it's called a hydrolysis reaction so this is both glycosidic bond and so you break that carbon oxygen bond and on the carbon you put an O H and on that oxygen you put the other H so that's where the water comes it's Oh H on the carbon and the other hydrogen on the oxygen okay so it's called a hydrolysis reaction so it turns out that sucrose if you've seen your drink it's surrounded by water right because as I taught you some some wise there's a lot of water in water right and so there's lots of water banging into that sucrose all the time in your drink but that sucrose is never gonna break down in your drink okay I can see it in your drink for years and years and years and it won't break down into glucose and fructose okay because for it to happen that glycosidic bond needs to be weakened okay basically you gotta bend that bond okay so water can come in react with you and that turns out to be really high potential energies that bond it's just not gonna Bend like that and just want to swim around in your drink but when it fits in the active site of the enzyme that catalyzes it it's called sucrase so a lot of times enzymes will end in a sed they try to tell you what they're doing so sucrase is the enzyme comes to Krause so while it's in the active site and surrounded by that big enzyme it can bend and strain that bond but it's stabilized by being surrounded by that enzyme and so then water comes in reacts with that and what's nice about that once that molecule reacts with water suddenly its glucose and fructose and has different intermolecular forces so it's attracted to that active site differently and it turns out usually that a little bit weaker and so I can leave the active site and then because what the enzyme is still good it can catalyze no sucrose molecule and so that enzymes not being you stop it can catalyze lots and lots of lots of super-smart molecules