Principle
At constant temperature and under constant pressure, a dissolved substance distributes itself between two immiscible liquids in a constant concentration ratio. This ratio is equal to the partition coefficient (distribution coefficient) of the substance examined in the given two-phase system.
Benefits
- Modern, easy-to-use photospectrometer
Tasks
- Measure the extinction of various concentrated solutions of trans-azobenzene in acetonitrile at constant wavelength. Subsequently determine the equilibrium concentrations (extinctions) of trans-azobenzene in the system n-heptane / acetonitrile after single and repeated distribution at constant temperature.
- Calculate the partition coefficients and effectiveness of the extractions from the experimental data and compare them.
Learning objectives
- Principles of thermodynamics
- Partial molar free enthalpy (chemical potential)
- Equilibrium between phases
- Distribution and extraction
- Nernst distribution equation
- Lambert-Beer law
- Photometry
Necessary accessories
- Precision balance 620g/0.001g