Is the freezing point of saltwater lower than that of fresh water?
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Is the freezing point of saltwater lower than that of fresh water? Why?
The freezing point is the temperature at which the vapor pressure of the pure solvent in the solid phase of a substance is equal to the vapor pressure of the pure solvent in its liquid phase. The freezing point of pure water is 0, at which temperature the vapor pressures of water and ice are equal. At 0 degrees, the vapor pressure of a salt-containing aqueous solution is lower than that of pure water; therefore, it does not freeze at 0 degrees. The freezing point of saltwater is lower than that of pure water, which is why seawater does not freeze easily.
The higher the salt content, the lower the freezing point and the higher the boiling point. This is in line with the principles of increased boiling point and decreased freezing point; the relevant formula is: T1 – T2 = kf * m. Here, T1 – T2 represents the degree of temperature change, kf is the molal freezing point depression constant for solvents, equal to 1.86, and m is the mass molar concentration of the salt