Freezing pt depression q

[inaccensa]

Since the freezing point depression was lower for Student 1, there must have been more particles for the same amount of mass. Thus Student 1 had an unknown with lower molecular weight. i don't understand how you can have more particles with the same mass, but lower molecular wt!!

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[lDanny]

"The freezing point depression of a solution containing a dissolved substance, such as salt dissolved in water, is a colligative property."

 

[zmatrix]

Since the freezing point depression was lower for Student 1, there must have been more particles for the same amount of mass. Thus Student 1 had an unknown with lower molecular weight. i don't understand how you can have more particles with the same mass, but lower molecular wt!!

Mass refers to the solvent. Remember the equation: ΔT(freezing) = K(freezing)*m;

m is MOLALITY (mol solute / kg of solvent) and NOT molarity. So depression was lower (greater) because there were more particles for the same amount of SOLVENT mass.