Science Buddies: "Ask an Expert"

is there any specific formula to calculate the moles and if so can someone please explain me the whole 3 equations things please!!!!

i understand that to get the molarity you divide moles by solute but what exactly are those numbers supposed to be

so the degrees of freezing point depression are calculated with the molar freezing point depression constant times the molarity but they never tell you how to get the molar freezing point depression constant

and didn't we got the freezing point depression in the equation above, so why is it again in a different form:

freezing point depression is equal to the molal freezing point depression content times the molarity times the van hoff factor(but above it is the same everything but you add the vann hoff thing)

please someone answer!!!!

and the test tube is fill with liquid of the concentration with the water, but then the styrofoam cup is fill with the concentration and ice????whattt??

Hello ilovescience37,

Please see Table 2 in the Procedure section. The molal freezing point constant is 1.86 and the van’t Hoff factors are 2 for NaCl and 1 for sucrose.

According to the procedure the styrofoam cup has and ice water/salt mixture in it. This is meant to be used to cool the test tubes containing your different NaCl and sucrose solutions.

I hope this helps. Please post again if you have more questions.

A. Norman