Vitamin K is involved in normal blood clotting. When 1.56 g of vitamin K is dissolved in 25.0 g of camphor, the freezing point of the solution is lowered by 5.23 °C. . Calculate the molar mass of vitamin K.
I posted this yesterday but I got the wrong answer and could use some step by step help?
Thanks
10 years ago
10 years ago
when Im getting my Kf do i change it from Celsius to Kelvin before i do my calculation?
10 years ago
You can but it doesn't matter. I think Kf for camphor is about 38 C/m (37.7 maybe?) or something like that.
10 years ago
What I meant was that Kf for camphor is 37.7 celsius/m or 37.7 Kelvin/m
10 years ago
Im sure i did this wrong but this is what i did
deltaT=Kfm
m=mols solute/ kg solvent
1.56g vitamin k/83.8g= 0.019
m=0.019/ 0.025 = 0.76
10 years ago
delta T=Kfm
-5.23=37.8m
-5.23-37.8 =m
m=-43.03
10 years ago
I think I wrote this:
delta T = Kf*m
Substitute and solve for m = molality
m = mols solute/kg solvent
Substitute and solve for mols solute.
mols = grams/molar mass
Substitute and solve for molar mass.
I don't think you followed the steps.
Take it one step at a time.
delta T = K*m
5.23 = 37.7*m
m = 5.23/37.7 = about 0.138m
Next.
m = mols solute/kg solvent
0.138 = mols solute/0.025
mols solute = 0.138 x 0.025 = about 0.00346 mols
Next:
mol = grams/molar mass
0.00346 mols = 1.56g/molar mass
molar mass = ?
10 years ago
nope. That isn't the way math works.
10 years ago
so i do 0.00346mols x 1.56 = 0.00539?
10 years ago
no.
0.00346 mols = 1.56g/molar mass
molar mass = 1.56/0.00346 =?
10 years ago
I see I spelled anonymous wrong.
10 years ago