Freezing of vinegar

Concentrated acetic acid freezes around seventeen degree Celsius. Water freezes at zero degree Celsius. But Vinegar has a very low freezing point , that is around minus two degree celcius.


Why is it so? How does mixing of substances change their melting/freezing points?




Think of ice as a highly ordered crystalline solid in which the water molecules are able to bind strongly with each other. How strongly the molecules bind to each other determines how much energy, in the form of heat, will be required to break them apart. 


Whether its ice or an altogether different type of solid, what happens when you disrupt these inter-molecular forces (i.e. hydrogen bonding, van der Walls forces, etc.) by introducing a second chemical substance? It requires less energy, less heat, to break apart the solid. Thus, it’s melting point is lowered. This is commonly known as "freezing point depression".


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