Depression in Freezing Point – Solution and Colligative Properties – Chemistry Class 12


Do subscribe to Ekeeda Channel and press bell icon to get updates about latest engineering HSC and IIT JEE main and advanced videos so friends in the last lecture we have studied the colligative properties like relative lowering of vapor pressure elevation boiling point and now we are going to study the third or negative property that is depression in freezing point and what is the depression fizzy part let us see so friends before knowing what is depression freezing-point we should know what is freezing point so according to the definition the freezing point is the freezing point of the substance may be defined as a temperature at which the vapor pressure of the liquid is in equilibrium with vapour pressure of the solid it’s very simple since you know the solid has low vapor pressure so therefore which means we have to convert the vapor pressure of a liquid such that it should have zero vapor pressure or it should have a vapor pressure equilibrium with solid means we are making the liquid converted into a solid so this temperature that we are providing to the liquid so as it would convert into a solid is known as freezing point four is something it’s a very common example that you know or thing that water which is present in liquid state in at ordinary temperature when we cool it at zero degree Celsius it starts freezing it’s converted into eyes and eyes when present in zero Degree senses or below zero Degree senses is said to be solid and hence freezing point is the temperature where a liquid is converted into a solid it basic thing now let us see what is depression in freezing point before that you should know what is the definition of it so it is the difference between the freezing point of pure solvent and freezing point of solution in this thing you should be very much careful and you should understand why I have written pure solvent first and then I have written solution the reason behind that is suppose I will give an example of it as you know the freezing point of water is zero degree Celsius so suppose in that quantity of water or in that fixed amount of water that s took I added volatile substance also I have added a non-return solute like urea or NaOH so what will happen the freezing point of the solution that is now being made by mixing water urea or water or NH the freezing point will be decrease suppose if it is because still -4 degree census so in this case which quantity will be the moon yes the quantity of the one which is pure component will be more then the solution and therefore I have written the formula s delta TF is equals to P naught F minus TF means P naught F has in larger value compared to the EF value so hence we should know and we should be very much careful that the freezing point of solution is always less than the freezing point of pure component or pure solvent so thank you friends for watching this video I hope you have got to know what is freezing point and what is depression in freezing point thank you so much and please do subscribe here are calm and let your friends share this too thank you so much

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  1. Hello Friends,

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  2. I think u donot know how to give a lecture.
    You stop and then start speaking.
    Make better your Engkish and speak flowly.
    You donot give full lecture and you leave the graph and derivation.
    So plz make better what i am saying to u as a student.

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