in Section four point two we'll be discussing about the various factors affecting solubility there are three factors that may affect solubility first solute fall in your direction secondly pressure and finally temperature first let's look at the solute solvent interaction now substances with similar intermolecular attractive forces or sometimes we see similar inter molecular interaction are soluble in one another in general polar compounds tend to dissolve in other polar compounds for example methanol and water methanol and water both of these are polar compounds the dominant intermolecular interaction for methanol is hydrogen bonding and the dominant intermolecular interaction for water is also hydrogen bonding since they have the same kind of inter molecular interaction we say that methanol is soluble in water or vice versa now generally nonpolar compounds tend to dissolve in other nonpolar compounds for example hexane and benzene or this two are the structures of hexane and benzene both are nonpolar compounds and the intermolecular interaction of hexane is London dispersion forces and for benzene is also London dispersion forces since they have the same kind of inter molecular interaction we say that hexane is soluble in benzene or vice versa so the general rule of thumb is this like dissolve like I repeat like this off like so generally polar compounds can resolve in other polar compounds and in general nonpolar substances can dissolve in nonpolar substances okay this is a pictorial form of what we have just discussed let's say there are two liquids water and liquid X so the blue dots here represent the water molecules the red dots here represent the liquid X molecules now if water is soluble in the queen x then this is the scenario that you will see you see that the water molecules and the liquid X molecules they are all evenly distributed in the solution however if water is not soluble in liquid eggs and this is what you see all the water molecules will group together stay together on one part of the mixture the liquitex molecules will also stay together on another part of the mixture so what is the key criteria for solubility the key criteria is this the attraction between a water molecule and a liquid X molecule must must be strong enough to overcome the initial attraction between two water molecules and between two liquid X molecules only under such scenario then one liquid is soluble in the secondary group ok from here let's look at a few examples state whether each solute is soluble in the respective solvent okay let's look at the first example at the nor and water so first you take note both of these compounds are polar the dominant intermolecular interaction in ethanol is hydrogen bonding for water is also hydrogen bonding since they have the same kind of intermolecular interaction we can see at the norm is soluble in water let's move on to example cephas right so example see you have two nonpolar compounds egain and hexane the intermolecular interaction in eaten is london dispersion forces for hexane is also London dispersion forces now since the intermolecular interaction of these two compounds is the same we say that attain is soluble in hexane and finally example be eaten and water so it in you take note is a non-polar compound water is polar the intermolecular interaction of 18 is London dispersion forces for water the dominant intermolecular interaction is hydrogen bonding so the intermolecular interaction of these two compounds are different so you can conclude even is insoluble in water k mix we will discuss about the effect of pressure on the solubility of a solute in this section we do not discuss about the effect of pressure on the solubility of a solid or a liquid right because a solid and a liquid cannot be compressed so we will only discuss about the effect of pressure on solubility of gas the pressure has a significant effect on the solubility of a gas in a liquid solvent and the solubility is directly proportional to the pressure of the gas above the solution so this is a picture of what we are going to discuss about in this section Lester off with the left hand side of the picture the bottom here is the liquid solvent the blue dots here represents the molecules of the gas solid so you imagine you start to apply some pressure on the gas molecules when you start to apply some pressure some of the gas molecules will be forced to dissolve in the liquid solvent so now you imagine you increase the pressure sample as you continue to increase the pressure more of the gas molecules will then be able to dissolve in the liquid-solid so the important point to note here is this the higher the applied pressure then more of the gas molecules will be able to dissolve in the liquid solvent so from pressure will move on to temperature the effect of temperature on solubility of gases and solids are different so we will treat Jesus and solids separately first let's look at the effects of temperature on solubility of gases the solubility of gases and liquids decreases with increasing temperature why is this so so this is the simple explanation energy of gas molecules increases with increasing temperature and therefore it is more likely for the gas molecules to escape from the liquid solvent at higher temperatures so you imagine initially you have a solution and now you see up the solution when you set up the solution the temperature of the solution will increase when the temperature increases the energy of the gas molecules also increases and some of these molecules will gain sufficient energy to escape from the solution thereby decreasing the solubility of gas at higher temperatures and now let's look at the effect of temperature on solubility of solids the solubility of solids in liquids increases with increasing temperature so this is different from that of gases why is this so energy of solvent molecules increases with increasing temperature the increase in energy of the solvent molecules will enable the solvent molecules to break the intermolecular interaction between the solute molecules more effectively thereby resulting in higher solubility of the so you imagine right you heat up right the solution when you heat up the solution the temperature increases when the temperature increases the energy of the solvent molecules also increase so when the energy of the solvent molecules increases this allows them to break the intermolecular interaction between solid molecules more effectively so in the end this results in higher solubility of the solute in the solution