Question

Thanks for the information Dr. Bob. Would you be able to work it out so that I can actually see the steps with the numbers and follow from there. The question was on Vitamin K from Sunday at 2:44pm which you answered at 3:45pm. Thanks again. I am looking to get a tutor since I don't understand the math in chem II.

Answer 1

You did not give the web address for melting point or Kf value for camphor. We don't need the melting point but we need Kf. The only value I could find on the web was 40 so you should confirm that.
delta T = Kf*m
delta T = 4.56
Kf = 40
Solve for m
4.56 = 40*m
m = 4.56/40 = 0.114

Then m = mols/kg solvent
m = 0.114
mols = ?
kg solvent = 25.0 g camphor
0.114 = mol solute/0.025 kg
mol solute(vit K) = 0.114 x 0.025 = 0.00285

mol = grams/molar mass
mol = 0.00285
g = 1.36
molar mass = ?

0.00285 = 1.36/molar mass
molar mass = 1.36/0.00285 = 477.2 which I would round to 477.

Answer 2

Thanks so much!