[hmrobinson09]

Can someone help me with this?
A solution of 2.24 x 10^-1g of an organic compound of unknown molecular weight in 1.664g of camphor gave a freezing point of 176.44 Celsius. The freezing point of camphor is 179.80 Celsius, and the freezing point depression constant K_f 39.7 Celsius/m. Calculate the molecular weight of the unknown.

[Borek]

What is formula for calculation of freezing point depression?

[sm2345]

Here is a formula which can be used to calculate the Molecular Weight of the solute:

ΔT_f = (k_fxW₂x1000)/(M₂xW₁)

where ΔT_f = Depression of freezing point
       
         k_f  = Molal Depression Constant(Cryoscopic constant)
     
         W₂ = Weight of the solute
 
         W₁ = Weight of the solvent &

         M₂ = Molecular Mass of the solute.

[Borek]

ΔT_f = (k_fxW₂x1000)/(M₂xW₁)

While it is not wrong, it may be confusing, as it makes several conversions in one step, instead of concentrating on the general concept:

ΔT_f = k_f m

where m is molality.