Freezing point depression



Principle

The freezing point of a solution is lower than that of the pure solvent. The depression of the freezing point can be determined experimentally using a suitable apparatus (cryoscopy). If the cryoscopy constants of the solvent are known, the molecular mass of the substance dissolved can be determined.

Benefits

• All relevant measured variables at a glance
• Experimentation made easy by intuitive operation
• With detailed experiment guide

Tasks

1. Determine the size of freezing point depression after dissolving a strong electrolyte (NaCl) in water.
2. Determine the number of ions into which the electrolyte dissociates.
3. Determine the molar mass of a non-electrolyte (hydroquinone) from the value of freezing point depression.
   

Learning objectives

• Raoult's law
• Cryoscopic constant
• Chemical potential
• Gibbs-Helmholtz equation
• Concentration ratio
• Degree of dissociation
• Van't Hoff factor

Necessary accessories

• Precision balance 620g/0.001g