IGCSE Chemistry: Experimental Techniques and Separation Methods

Vocabulary practice flashcards for IGCSE Chemistry focusing on experimental techniques, measurement instruments, laboratory apparatus recognition, purification processes, and analytical chromatography.

Burette

A graduated piece of laboratory glassware used to accurately deliver variable volumes up to $50\,\text{cm}^3$ of liquid, with graduations readable to the nearest $0.1\,\text{cm}^3$.

Volumetric Pipette

A piece of glassware calibrated to deliver a single fixed volume of liquid (such as $25\,\text{cm}^3$) with very high precision.

Measuring Cylinder

A piece of laboratory glassware used to measure approximate liquid volumes where fast addition is required and extreme accuracy is not critical.

Volumetric Flask

A specialized flask designed to make up a solution of known concentration with high accuracy by filling solvent exactly to a single graduation mark.

Gas Syringe

A calibrated glass syringe fitted with a low-friction plunger, designed specifically to collect and measure volumes of gases evolved during an experiment.

Filtration

A separation method used to separate an insoluble, undissolved solid suspended in a liquid by passing the mixture through porous filter paper.

Filtrate

The clear liquid that passes through the filter paper during a filtration procedure.

Residue

The insoluble solid trapped on the filter paper during filtration, or the non-volatile solid remaining in a flask after distillation.

Decantation

A separation technique where a suspension of large, heavy insoluble solid particles is allowed to settle to the bottom and the liquid above is carefully poured off.

Crystallization

A technique used to obtain pure solid crystals from a solution by evaporating the solvent to saturation point, allowing it to cool and crystallize, then filtering and drying.

Simple Distillation

A method used to separate and collect a volatile liquid solvent from a non-volatile solute through boiling followed by condensation in a condenser.

Anti-bumping Granules

Small inert chips added to a round-bottom distillation flask that promote even, gentle boiling and prevent the formation of dangerously large vapor bubbles.

Fractional Distillation

A separation method used to separate two or more miscible liquids with different boiling points by using a fractionating column to facilitate repeated vaporization-condensation cycles.

Miscible Liquids

Liquids that mix completely with each other in all proportions to produce a single, homogeneous liquid phase.

Immiscible Liquids

Liquids that do not mix or dissolve in one another and separate into distinct layers based on density differences.

Separating Funnel

A pear-shaped glass apparatus fitted with a stopcock tap, used to separate two immiscible liquids by tapping off the denser layer from the bottom.

Paper Chromatography

An analytical technique used to separate and identify dissolved components in a mixture based on their relative solubility in a mobile solvent versus their attraction to the stationary paper.

$R_f$ Value

The retention factor in chromatography, defined as the ratio of the distance traveled by a substance to the distance traveled by the solvent front ($R_f = \frac{\text{distance moved by substance}}{\text{distance moved by solvent}}$).

Locating Agent

A substance (such as ninhydrin) sprayed onto a chromatogram that chemically reacts with colorless sample spots to make them visible as colored spots.

Solvent Front

The uppermost horizontal line reached by the mobile solvent phase as it moves up the chromatography paper.

Fullerenes

A family of solid carbon allotropes discovered in 1985 (such as $C_{60}$) formed of hollow cage-like spherical structures in which each carbon atom is bonded to three others.

Ester Linkage

The functional group linkage with the structure $-COO-$ formed between a carboxylic acid and an alcohol.

Saturated Solution

A solution that contains the maximum concentration of dissolved solute possible at a given temperature, such that no more solute can dissolve.

Volatile Liquid

A liquid with a relatively low boiling point that evaporates readily into vapor at room temperature.

Cryolite ($Na_3AlF_6$)

An ionic compound added to molten alumina ($Al_2O_3$) during the industrial electrolysis of bauxite to significantly reduce its melting point and improve conductivity.

Amphoteric Oxide

An oxide, such as aluminium oxide ($Al_2O_3$), that reacts with both acids and bases, allowing it to dissolve in aqueous sodium hydroxide while basic oxides remain insoluble.

Thistle Funnel

A long, narrow glass tube terminating in a flared, cup-like reservoir, used to add liquids into a closed reaction flask below liquid level.

Pestle and Mortar

A pair of heavy laboratory tools used together to crush, grind, and pulverize solid chemicals into fine powders.

Watch Glass

A shallow, circular concave glass surface used for evaporating small liquid droplets, weighing solids, or covering beakers to prevent contamination.

Evaporating Dish

A wide, shallow porcelain basin with a pouring spout designed to heat solutions and drive off liquids to leave solid residues.

Crucible and Lid

A heat-resistant ceramic cup and cover used to heat solid chemical compounds to very high temperatures over a direct flame.

Teat Pipette

A small glass or plastic dropper tube fitted with a compressible rubber bulb at one end, used to transfer liquids drop by drop.

Fractionating Column

A vertical glass column containing glass beads or rods fitted above a distillation flask, which provides a high surface area for repeated evaporation and condensation during fractional distillation.