Separations And Purifications Flashcards
What are separation techniques?
Used to transform a mixture of substances into two or more distinct products
What is purification?
The physical separation of a chemical substance of interest from foreign or contaminating substances
What is extraction?
The process by which a solute is transferred (extracted) from one solvent and placed in another. This is only possible if the two substances are immiscible
What is chromatography ?
The separation of a mixture of compounds by their distribution between two phases: one stationary and one moving. Molecules are separated based on differences in polarity and molecular weight
What is gas liquid chromatography?
- Stationary phase is a liquid absorbed to an inert solid.
- Mobile phase is a gas which is unreactive to stationary phase and the substance being seperated
- Sample injected into column
- Some molecules will be separated based on how fast they move through, etc
What is thin-layer chromatography?
- Solid liquid technique
- Stationary phase is a type of finely divided polar material such as silica gel which is thinly coated onto a glass plate
- Molecules in the substance with greatest polarity will bind more strongly to plate and thus not rise
What is distillation?
The process by which compounds are separated based on differences in boiling points. A classic example of simple distillation is the separation of salt from water. Only works if one compound is more volatile - fractional distillation can be used if there is not much difference
What is recrystallisation?
Impure, solid organic compound is dissolved in hot solvent, and then solvent is slowly cooled to allow the pure compound to reform or recrystallise, while leaving the impurities behind in the solvent
