hello everybody my name is Iman welcome back to my YouTube channel today we're going to be talking about analyzing organic reactions and we're going to cover the following objectives in this chapter first we're going to talk about acids and bases we're going to define the bronstit Lorry and the Lewis definitions of acids and bases and then we're going to move into a discussion about acid-base strength and common functional groups next we'll move into a detailed discussion about nucleophiles electrophiles and leaving groups and then we're going to talk specifically about nucleophilic substitution reactions third we'll move into oxidation reduction reactions here we're going to first Define oxidation and reduction as well as oxidizing and reducing agents and then we're going to talk about reactions we should be familiar with for the MCAT fourth we're going to talk about chemo selectivity and all that entails and then we're going to end the chapter with a step-by-step discussion to problem solving organic chemistry reaction questions let's go ahead and get started with our first objective and talk about acids and bases now over the last century chemists have used different definitions to identify compounds as either acids or basis all right and we see the emergence of different definitions each more inclusive than the formal one all right now in general chemistry you you learn the erroneous definition the bronstant Lorry definition as well as the Lewis definition any mention of the Arrhenius definition on test day is most likely going to be a comparison to other definitions of acids the Arrhenius definition is actually by far the most restrictive it defines an acid as one that will dissociate to form an excess of hydrogen ion Solutions ions in solution and it defines a radius space as one that will dissociate to form an excess of hydroxide ions in solution but as we cover here the bronstant Lorry and the Lewis acid base definitions we're going to see how they are more inclusive all right and it is the bronstant Lorry and the Lewis definitions that are going to predominate on the MCAT all right so let's first start all right covering the bronstant Lorry definition a bronstant lorry acid is a species that donates hydrogen ions all right it donates hydrogen ions a bronson-lory based on the other hand is a species that can accept all right that it can accept hydrogen ions all right so a broad acid is a species that donates hydrogen ions while a bronstant-lory base is a species that accepts them now the advantage of this definition over the Arrhenius one is that it is not limited to aqueous solution so for example hydroxide ammonia they're all bronstant Lorry bases because each has the ability to accept a hydrogen ion however ammonia NH3 cannot be classified all right as a Arrhenius base because they don't dissociate to produce an excess of hydroxide ions in solution all right so in a bronze that Laurie acid this species donates hydrogen ions while a bronze stunt Lorry base is a species that accepts some that is already more inclusive than the Arrhenius acid and base definition all right now something to keep in mind all right something to keep in mind is that every arrhenous acid or base can be classified as a bronstant lorry acid or base all right this logic doesn't work the other way all right so that's bronson-lory acid and base let's talk about the Lewis definition all right a Lewis acid is defined as an electron pair acceptor while a Lewis base is defined as an electron pair donor all right now there is an intuitive approach to understand the differences in the definitions we've discussed so far the Lewis definitions relies on a behavior that is not vastly different from the bronstant-lory interactions the only difference really is the focus so for bronstant Lorry acids and bases all right we follow the exchange of hydrogen ions which is essentially a naked proton in the Lewis definition the focus of the reaction is no longer on the proton but instead the electrons forming the coordinate covalent bond all right now note also again that the Lewis definition is the most inclusive definition every Arrhenius acid is also a bronstant lorry accident every bronstant-lauric acid is also a Lewis acid and likewise for basis the thing to remember though is that the the opposite the converse is not necessarily true all right now on the MCAT you're going to encounter Lewis acids in the contexts of organic chemistry reactions because Lewis acids are often used as catalysts we're going to see a little bit of that in this chapter and in the chapters to follow now one more thing that I want to Define all right well like our definition we said that the Lewis definition is the most inclusive all right and we said that every Arrhenius acid or base is a bronstant-lory acid and base in every bronstant-lauric acid and base is a Lewis acid and base and we see we see that hierarchy and that relationship in this figure right here now another thing we want to quickly Define is amphoteric species an amphoteric species is one that reacts like an acid in a basic environment and like a base in an acidic environment so in the bronze that Laurie sends an amphoteric species can either gain or lose a proton making it anthropodic as well so on the MCAT water is the most common example all right and that is an important fact that we should keep in mind as we move through our organic chemistry series all right now we've defined acids and bases all right the next thing that we really want to talk about is acid base strength all right and to to talk about acid and based strength we're going to have to recall a very important concept that we talked about in general chemistry and that is the acid dissociation constant also denoted as k a so this acid dissociation constant when we talked about it we said that it measures the strength of an acid in solution so in the dissociation of an acid all right something that we see here right we're starting off with an acid Aha and it dissociates into hydrogen ions and a minus all right we can go ahead and write the equilibrium's constant from this reaction all right we can write the acid dissociation constant we can say Ka is going to be equal to the concentration of the products over the concentration of the reactants so here h plus and a minus are the products and so the numerator is the concentration of both of those species all right over the concentration of the reactants which is our acid h a all right so this is the acid dissociation constant now from this we can calculate something called the pka all right the pka is just the minus log of your acid dissociation constant all right so PKA is equal to minus log Ka all right now what you're going to see here all right from this relationship is that more acidic molecules will have a smaller or even negative PKA whereas more basic molecules will have a larger PKA now acid through the pka that's below minus two they're considered very strong acids or which you know they're considered strong acids ones that almost always dissociate completely in aqueous solution all right weak organic acids they often have a PKA values anywhere between -2 and 20. all right now here what we see are some common functional groups and they're Associated PKA values all right so over here what we have here is an alkane right just carbon a hydrocarbon molecule carbon hydrogen single bonds all right this is alkane all right we see that it has APK of around 50. all right so that is remember at this level this is you can consider this a weak acid all right it's conjugate strongest base all right then we have an alkene carbon-carbon double bond that's its PKA all right we have NH3 we have a um amine here all right that's it's PKA alkyne all right and so on and so forth this table gives us the respective PKS for a lot of very important functional groups that we should be familiar with for the MCAT all right so again here we have an alkane this is an alkena we can go ahead and write these out or at least note the most important ones and write them out so let me just erase some of this and we can go ahead and start writing the names for some of these functional groups all right this is going to be alkane that's that functional group all right double bonds here Del carbon carbon double bonds alkene all right here we have and Amine all right and it's respective PKA all right this is an alkyne with a Y all right carbon carbon triple bond um something else that's going to be important for us to be familiar with all right is this is an alcohol all right this is an alcohol group all right this is water all right fantastic this is a fennel okay that's another important one to know okay this is anhydride all right let's write this out and hydride all right this is not really a functional group The functional group is the alcohol but I wanted to give you the name of the molecule all right this is anhydride this right here um is a carboxylic acid so we can write that down carboxylic acid all right fantastic and this right here is a hydronium ion all right H3 o plus all right this is um well this is a halide chloride right here if we had a molecule that had a carbon some sort of carbon attached to a halogen we'd call that an alkyl halide all right and those are the important ones we should definitely keep it in mind along with their PKA values so again this is a table of PKA values for common functional groups that we should be familiar with all right and again more acidic molecules will have a smaller or even negative PKA more basic molecules will have a larger PKA now generally also just looking at this table bond strength decreases we know bond strength decreases going down the periodic table and acidity therefore increases also the more electronegative an atom the higher the acidity and when these two Trends oppose each other low bond strength is going to take precedence all right so we talked about acids and bases we've defined them under the bronstant Lorry definition and Lewis and Lewis definition we also talked about acid-base strength and we talked about common functional groups and their PKA values all right with that we have covered objective one I'm gonna pause the video here in the next video we're going to move into objective two which is all about nucleophiles electrophiles and leaving groups let me know if you have any questions comments concerns down below other than that good luck happy studying and have a beautiful beautiful day future doctors