Problem: Using freezing point depression to find molecular weightMass of Lauric Acid (g)                                                                     8.003Mass of benzoic Acid (g)                                                                   1.010Freezing temperature of pure lauric acid (C°)                                   43.84Freezing temperature of the benzoic acid-lauric acid mixture (C°)   39.05a. 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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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 = K * 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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