A) If the freezing point depression constant for camphor is 40°C·kg/mol, determi
ID: 911654 • Letter: A
Question
A) If the freezing point depression constant for camphor is 40°C·kg/mol, determine the molal concentration of isoborneol in the product given that the melting point of your camphor sample is 157°C and the true melting point of camphor is 179°C.
B) Given the molality of isoborneol is 0.340 mol/kg, what is the percent by mass of isoborneol in the product?
C) Assume the molality of isoborneol in your product is 0.275 mol/kg. What is the melting point of your impure sample given that the melting point of pure camphor is 179°C and its freezing point depression constant is 40°C·kg/mol?
D) Assume you begin with 9.2 mmol of camphor. What is your percent yield if your experimental yield is 0.045 g?
Explanation / Answer
K = 40°m
find m of isoborneaol
T = 157°C
Tf = 179°C
dT = K*m
(179-157) = 40*m
m = (179-157)/40 = 0.55 mol/kg
b)
m = 0.34 mol/kg
find % by mass
MW of isoborneol = 154.25
mass = mol*mw = 0.34*154.25 = 52.445 g
MT = 52.445 + 1kg = 1.052445
%M = 52.445/1052.45 *100 = 4.983%
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