Mixtures And Separation Methods Review

Comprehensive vocabulary flashcards covering the characteristics of substances, types of mixtures, solubility, and liquid-solid separation techniques as detailed in the lesson notes.

Element

A pure substance that contains one type of atom and cannot be decomposed by chemical means into simpler substances.

Compound

A pure substance that contains two or more different types of elements chemically combined together in a fixed ratio, where properties of the elements change.

Mixture

An impure substance made up of two or more different elements and/or compounds physically combined together in variable proportions.

Pure Substance

A substance with fixed and constant composition and properties, having a sharp melting point and boiling point (e.g., pure water boils at $100\,^{\circ}C$).

Impure Substance

A substance that melts or boils over a range of temperatures; impurities generally lower the melting point and increase the boiling point.

Homogeneous Mixture

A mixture that has a uniform composition throughout, such as a solution.

Solution

A homogeneous mixture formed when one or more solutes dissolve in a solvent, with solute particles smaller than $1\,nm$ in size.

Suspension

A heterogeneous mixture where particle size is $> 1000\,nm$; light does not pass through, particles settle on standing, and they can be filtered.

Colloid

A heterogeneous mixture with particle sizes between $1-1000\,nm$ that scatters light, does not settle on standing, and cannot be filtered.

Gel

A type of colloid consisting of solid particles dispersed in a liquid, such as gelatin or jelly.

Emulsion

A type of colloid consisting of liquid droplets dispersed in a liquid, such as mayonnaise or milk.

Solubility

The maximum mass of solute that will saturate $100\,g$ of solvent at a given temperature.

Saturated Solution

A stable solution in which the maximum amount of solute has been dissolved at a given temperature.

Supersaturated Solution

An unstable solution that temporarily contains more than the saturation amount of solute than the solvent can hold at a given temperature.

Rule of "Like dissolves like"

A rule of thumb stating polar solutes dissolve in polar solvents (e.g., salt in water), and non-polar solutes dissolve in non-polar solvents (e.g., iodine in hexane).

Filtration

A method used to separate an insoluble solid from a liquid based on a difference in particle size.

Evaporation

A method used to separate and retain a solid solute from a liquid solvent based on a difference in boiling points; crystals remain after heating to dryness.

Crystallisation

A method used to obtain pure crystals from a solution by heating until saturated and then cooling; used for salts that decompose on heating.

Sublimation

A method to separate substances like iodine, ammonium chloride, naphthalene, or dry ice ($CO_2$) from a mixture because they change directly into vapour when heated.

Simple Distillation

A method used to obtain a pure solvent (distillate) from a solution by heating to create vapour and then cooling it in a condenser.

Fractional Distillation

A method used to separate two or more miscible liquids with different boiling points when the difference is less than $25\,^{\circ}C$.

Separating Funnel

A tool used to separate immiscible liquids that have different densities, such as a mixture of oil and water.

Paper Chromatography

A method used to separate components based on different solubilities in the same solvent (mobile phase) as they move across a stationary phase.

Rf Value

A ratio calculated as $\frac{\text{distance moved by a solute}}{\text{distance moved by solvent front}}$.

Locating Agent

A substance sprayed on a chromatogram to produce coloured compounds and make colourless spots visible.

Bagasse

The sugar cane fibres removed after crushing, used as fuel in the boiler station to produce steam.

Seeding

The process of adding pure sugar crystals to thick supersaturated syrup to cause the formation of crystals.

Centrifugation

The separation method used to separate sugar crystals from molasses.