Water Freezing Point Depression 1

[moemantha]

I have a water analysis showing the individual Cations and Anions and their corresponding mass fractions in the water sample of interest. Does anyone know how to calculate the Freezing point of a water solution using this information?

 

[SeanB]

Refer to CRC Handbook of Chemistry and Physics.

 

[strane]

Use a basis of 1Kg of water sample. Using the ion's weight fraction find out how many grams of each there is. Then using the ion's atomic weight, find out how many moles of each are present. Add up all the moles and divide by the Kg of ion free water. This will give you the total ionic molality of the solution (m). Then use the equation for freezing point depression:

(freeze point of solution [degrees C]-freeze point of water [degrees C]) = -K * m.

Where K is the molal freezing point dpression constant for water [1.855 degrees C per mole], and m is the molality of the ions in solution calculated above.