Ch.12 - SolutionsWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds

Solution: 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.   

Problem

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.