Question

to Find Molecular Weight Worksheet DATA TABLE Mass of lauric acid (g) | 8.00 g Mass of benzoic acid (g) | 1.03 g Freezing temperature of pure lauric acid (°C) | 42.1 °C Freezing point of the benzoic acid-lauric acid mixture (°C) | 37.8 °C DATA ANALYSIS 1. Calculate molality (m), in mol/kg, using the formula ?t = Kf × m. The Kf value for lauric acid is 3.9°C?kg/mol. 4.3 °C / 3.9 = 3.9 °C / 3.9 K/mol × m m = 1.102 mol/kg 2. Calculate moles of benzoic acid solute, using the molality and the mass (in kg) of lauric acid solvent. 1.102 / 1000 × 8 = 8.82 × 10^-3 mol benzoic acid Mass of lauric acid = 8 / 1000 = 0.008 kg

          to Find Molecular Weight Worksheet

DATA TABLE

Mass of lauric acid (g) | 8.00 g
Mass of benzoic acid (g) | 1.03 g
Freezing temperature of pure lauric acid (°C) | 42.1 °C
Freezing point of the benzoic acid-lauric acid mixture (°C) | 37.8 °C

DATA ANALYSIS
1. Calculate molality (m), in mol/kg, using the formula ?t = Kf × m. The Kf value for lauric acid is 3.9°C?kg/mol.
4.3 °C / 3.9 = 3.9 °C / 3.9 K/mol × m
m = 1.102 mol/kg

2. Calculate moles of benzoic acid solute, using the molality and the mass (in kg) of lauric acid solvent.
1.102 / 1000 × 8 = 8.82 × 10^-3 mol benzoic acid
Mass of lauric acid = 8 / 1000
= 0.008 kg

to Find Molecular Weight Worksheet

DATA TABLE

Mass of lauric acid (g) | 8.00 g
Mass of benzoic acid (g) | 1.03 g
Freezing temperature of pure lauric acid (°C) | 42.1 °C
Freezing point of the benzoic acid-lauric acid mixture (°C) | 37.8 °C

DATA ANALYSIS
1. Calculate molality (m), in mol/kg, using the formula ?t = Kf × m. The Kf value for lauric acid is 3.9°C?kg/mol.
4.3 °C / 3.9 = 3.9 °C / 3.9 K/mol × m
m = 1.102 mol/kg

2. Calculate moles of benzoic acid solute, using the molality and the mass (in kg) of lauric acid solvent.
1.102 / 1000 × 8 = 8.82 × 10^-3 mol benzoic acid
Mass of lauric acid = 8 / 1000
= 0.008 kg

Added by Eric G.

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