 right on physical property physical property they are not much right on from Steven to C4 first one from carbon number one to carbon number four the molecules are colorless, odorless, gas exists in alkanes, physical properties are fine methane to beauty one carbon to four carbon one carbon to four carbon from methane to beauty colorless, odorless, gas C5 to C17 right on C5 to C17 colorless, odorless, liquid not colorless, odorless, liquid no C5 to C17 C18 onwards C18 onwards it is wax like solid liquid wax like solid right on boiling point is directly proportional to boiling point is directly proportional to molecular mass and inversely proportional to branching right on branching increases branching means what if you have butane in it I saw butane, butane will have more boiling point with branching surface area decreases hence boiling point decreases right on as branching increases decreases as branching increases surface area decreases and hence the boiling point next right on matting point right on matting point matting point increases with increase in right on matting point increases with increases with the increase in increases with the increase in the number of carbon atom right on alkanes with even number of carbon atom gains with even number of carbon atom carbon atom has higher melting point than those of odd number carbon atom alkanes alkanes you are talking about alkanes see when you have even number of carbon atom symmetry is there and hence matting point is more if you compare this propane butane butane has more melting point than this thing because of symmetry its matting point is here when you have symmetry like this packing is better packing more melting point that's why trans isomer also has better matting point more matting point it is not having a regular order but obviously the number of carbon atom is also affected this so it won't have a definite order like we are saying as carbon number increases then boiling that's how we get our say okay next right on chemical property chemical properties is nothing but you see chemical reactions chemical reaction so chemical reaction first one right down photo halogenation have you heard about photo halogenation? what is photo halogenation? halogenation of life this reaction follows free radical mechanism this reaction follows free radical mechanism and the reactivity order is for alkyl group ch4 then 1 degree 2 degree and then mechanism means free radical forms the activity of alkyl group like how much energy do you have? this is not right no means how fast the reaction goes you see so 3 degree alkyl this if you have you have branch over here then the reaction goes there so normally CH4 is considered a radical thing right? no no so why is this what thing do you think you are wrong? carbon, carbon attack carbon in a present you are right so when this attacks over here you get 3 degree radical which is most in that's why it goes faster more stable radical forms faster that's why the reaction goes faster right now there are 2-3 things you have to memorize you are the first point to write down in this only fluorination, fluorination 2-3 points for each of these reactions you have to memorize fluoration write down it is it is highly exothermic difficult to control that's why generally fluorination we won't do in this reaction exothermic highly exothermic and difficult to control if we use this method then we when we allow this reaction to proceed in the in presence of nitrogen we do this like it's written in the book like this reaction fluorination takes place in the environment of nitrogen which reduces the rate of the reaction so we can control of it but fluorination usually we don't right second point to write down fluorination fluorination exothermic exothermic non-selective exothermic non-selective non-selective exothermic non-selective and we can control this reaction difficult but we can control let's write down bromination it is selective endothermic in nature selective endothermic in nature selective means what you get only one type of product suppose this is the alkane and you are doing bromination of it or you haven't given the reaction for proteination we are to which etch new so selective means one type of product forms into this means wherever we get most stable radical they're only bromine so this 3d radical is this here so the product of this will be so it's selective we are getting only one type of product if you're doing chlorination suppose the molecule is this right and you're doing chlorination so chlorination is what it is non-selective means we do not have control over this so you can get two mixture of two products here one is this one degree primary alkane line and another one is this secondary alkane both you can get this means it is non-selective this means it is selective you can also calculate the percentage of this forms and percent of this forms it's possible is basically we'll do that we'll do that first you write down we will do this which is easier to what both get and so that means non-selective the reason for this also you'll understand once we'll discuss the percentage operation of this you'll understand the reason of this but first you write it down then we'll see how do we calculate this okay so must remember this bromination is selective we'll write down only most stable product most stable radical and then we'll attach last one we write down the third fourth one iodination right now this reaction is reversible and takes place in presence of an oxidizing agent this reaction is reversible and takes place in presence of an oxidizing agent like iodic acid h i o 4 this is what it says in presence of an oxidizing agent iodic acid write on h i o 4 or h n o 3 it is selective for this one if you have iodination in presence of h nu right reaction is reversible in nature so it forms this product iodine and h i also it forms so if the if you do not use an oxidizing agent the reaction has a tendency to go into backward direction right so when you use an oxidizing agent suppose h i o 4 so what it does iodic acid h i o 4 it oxidizes this into i2 and hence you continuously convert this into i2 and the reaction goes in forward direction right so that is why we are using this iodic acid that's why the reaction of iodic acid is very difficult to break down HF bond also if you know what you're talking about chlorination in chlorination why the reaction is very difficult because very high amount of energy releases and there are chances of catching this and say that you are control the reaction that's what you want we usually don't do chlorination write on this this table is rocking secondary and tertiary write on the heading percent is composition percent is composition chlorination and rumination this is the relative rate of chlorination for hydrogen active relative reactivity you can say relative rate of the reaction means the rate of reaction of secondary hydrogen with chlorine is 3.8 times more than to that of primary and then five times to more than to that of this ratio of this is one is to this now in bromination you see the tertiary hydrogen has the highest reactivity right and the difference is used that's why we get military 3.8 no in bromination why we get tertiary because its reaction is relative rate is very high that's why the chances to get tertiary product is maximum over there and hence it is selective 3.8 and 5 are comparable right we'll get both problems yes so all those tertiary hydrogen that you have that will react easily because it's rate is more means what those hydrogen has maximum tendency to react right so this is experimental data right through how do we calculate the percentage so what is this percentage company what are the products we get into this what's the most huh where are the three what about one two one two huh Now, how many 2 degree hydrogens we have here in this molecule, how many 2 degree hydrogens How many 2 degree hydrogens, 2 degree hydrogens, 2 plus 2 4, how many 1 degree, 6, do we have 3 degree, 0, so Now, to find out the composition of these two, what we calculate, the reactivity of suppose this is A and this is B or amount will rise, amount of A the relative amount that forms Since A is secondary, so number of secondary hydrogen into reactivity of that, what is that, 3.8, secondary, so 4 into 3.8, what is this value, 15.2 For B, 6 into 1 that is 6, now percentage of A if you have to calculate percentage of A that will be its composition divided by total into 2, it is this one, this one, it is actually total reactivity also you can say terms of that, eventually you have to find out percentage, you have to take the ratio and multiply So, we have 4 hydrogen and the hydrogen of reactivity of 1 hydrogen is 3.8, 3.8 into 4, better you write reactivity not amount, total reactivity of 2 degree Does not change the answer because anyways you have to find out percentage Okay, so 4 secondary hydrogen we have and reactivity of 1 is 3.8, total is 4 into 3.8 this, for primary 6 into 1 is 6, total is 21.2, so for A it is this by total into 100 For B what we will write, 100 minus and or Okay, that is how we calculate the percentage composition of this, in rumination the reactivity is quite high, see the comparison 20 times of this Okay, that is why we only write the tertiary or secondary if possible and it is selective Okay, done, understood Finished