Answer:
The molar mass is 227 g/mol
Explanation:
Step 1: Data given
Mass of unknown nonelectrolyte = 3.90 grams
Mass of water = 9.60 grams
Freezing point of the solution = -3.33 °C
Kf = 1.86°C/m
Nonelectrolyte has a van't Hoff factor = 1
Step 2:
If you know the number of moles, and you know that is equivalent to 1.00 g, you can get molar mass.
∆T =i*m*K
f
⇒ ∆T = difference in temperature between freezing point of solution and pure water = 3.33 °C
⇒ Van't hoff factor of the nonelectrolyte = 1
⇒ molality = moles nonelectrolyte / mass water
⇒ Kf = freezing point constant = 1.86 °C/m
3.33 = (1)(m)(1.86)
m = 1.79 molal = 1.79 moles / kg H2O
Step 3: Calculate moles nonelectrolyte
molality = moles / mass H2O
moles = molality * mass H2O
Moles = 1.79 molal * 0.0096
Moles = 0.017184 moles
Step 4: Calculate molar mass of nonelectrolyte
Molar mass = mass / moles
Molar mass = 3.90 grams / 0.017184 moles
Molar mass = 227 g/mol
The molar mass is 227 g/mol
