Using freezing point depression to find molecular weight
Mass of Lauric Acid (g) 8.003
Mass of benzoic Acid (g) 1.010
Freezing temperature of pure lauric acid (C°) 43.84
Freezing temperature of the benzoic acid-lauric acid mixture (C°) 39.05
a. Calculate molality (m), in mol/kg, using the formula Δt = Kf * m. The Kf value for lauric acid is 3.9°C•kg/mol.
b. Calculate moles of benzoic acid solute, using the molality and the mass (in kg) of lauric acid solvent.
c. Calculate the experimental molecular weight of benzoic acid, in g/mol.
d. Determine the accepted molecular weight of benzoic acid from its formula, C 6H5COOH.
e. Calculate the percent discrepancy between the experimental and accepted values.
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