Separating Mixtures and Chromatography Techniques

Vocabulary flashcards covering chromatography, distillation, evaporation, filtration, and related separation techniques from the lecture notes.

Chromatography

An analytical technique that separates a mixture into its components by differences in partition coefficients between two or more phases; invented by Mikhail S. Tsvet and named from chroma (color) + graphein (to write.

Mikhail S. Tsvet

Russian-Italian botanist who invented chromatography (1872–1919).

Adsorbent

A material used in chromatography that holds components on its surface as the stationary phase to aid separation.

Partition coefficient

Ratio of a chemical’s concentration between two immiscible phases; differences in this value drive separation in chromatography.

Pigments (xanthophylls, carotenes, chlorophylls)

Plant colors separated by chromatography; xanthophylls and carotenes are carotenoids; chlorophylls give greens.

Liquid chromatography

A chromatography method using a liquid mobile phase to separate solutes in solution (often analyzing metal ions and organic compounds).

Gas chromatography

A chromatography method for volatile gases; uses a carrier gas (commonly helium) to move the sample through a column; used in forensics, drug/alcohol analysis, bomb detection.

Helium

Common carrier gas used to move the gaseous sample through the GC column.

Thin-layer chromatography

Chromatography using an absorbent layer on flat glass plates; a quick method to check purity and detect residues (e.g., pesticides).

Paper chromatography

Chromatography using paper as the stationary phase; relies on capillary action to move solutes; used for amino acids, anions, RNA fingerprinting, and more.

Distillation

A method to separate two liquids with different boiling points by vaporizing, condensing, and collecting the distillate.

Boiling point

Temperature where a liquid’s vapor pressure equals atmospheric pressure.

Simple distillation

One-stage distillation where the most volatile component vaporizes first and is condensed and collected as distillate.

Distillate

The condensate that is collected during distillation.

Fractional distillation

Multiple successive distillations in an automatic setup, using a fractionating column to improve separation by repeated vaporization and condensation.

Fractionating column

A column packed with material that promotes repeated vaporization/condensation to separate close-boiling components.

Steam distillation

Distillation used for heat-sensitive components; steam lowers the effective boiling point so distillation can occur below 100°C.

Dalton’s law of partial pressures

For nonreacting gases, the total vapor pressure equals the sum of the individual vapor pressures.

Vacuum distillation

Distillation conducted under reduced pressure to lower boiling points and prevent decomposition of heat-sensitive compounds.

Evaporation

Process of separating soluble solids from solutions by solvent removal; the solute is recovered, the solvent is not.

Solute

Substance dissolved in a solvent.

Sea salt

Salt formed from the natural evaporation of seawater (an evaporation-based separation).

Filtration

Separation of undissolved or insoluble particles from a liquid using a filter; residue remains and filtrate is the liquid that passes through.

Residue

Solid left behind after filtration.

Filtrate

Liquid that passes through the filter.

Filter paper

Paper used to separate suspended particles from a liquid during filtration.

Sedimentation

Settling of sediments by allowing the mixture to sit undisturbed.

Decantation

Pouring off a clear liquid to separate solids from the liquid.

Centrifugation

Spinning a heterogeneous mixture to use centrifugal force to accelerate separation into a residue and centrifugate.

Centrifugate

The liquid portion that is separated after centrifugation.

Magnetic separation

Separation technique using magnets to remove magnetic materials from a mixture.

Manual separation

Physically separating larger or distinct components by hand.

Sifting

Separation of particles by size using a sieve or screen.

Sublimation

Solid turns directly into gas and deposits on a cooler surface, allowing separation of a sublimable substance (e.g., iodine) from non-sublimable material.

Separatory funnel

Apparatus for separating immiscible liquids; the denser liquid settles below; stopper and stopcock release the upper or lower layer as needed.

Immiscible

Liquids that do not mix to form a single phase.

Layer

One of two immiscible liquid phases in a separatory funnel (upper or lower) based on density.

Stopper

Cap used to seal the separatory funnel during mixing.

Stopcock

Valve used to release the lower layer in a separatory funnel.