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Closed glass tube containing a gas under low pressure, with electrodes near the ends and a luminescent screen at the end near the positive electrode, produces cathode rays when high voltage is applied.

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Fossil Fuels

Substances consisting largely of hydrocarbons, derived from decay of organic materials under geological conditions of high pressure and temperature (metamorphism) include coal, petroleum, natural gas, peat and oil shale.  For further information see Fuel Chemistry

Heat of Crystallization

The amount of heat that must be removed from one gram of a liquid at its freezing point to freeze it with no change in temperature.

Net Ionic Equation

Equation that results from canceling spectator ions and eliminating brackets from a total ionic equation.

Dispersing Medium

The solvent-like phase in a colloid.

Plasma

A physical state of matter which exists at extremely high temperatures in which all molecules are dissociated and most atoms are ionized.

Chemical Change

A change in which one or more new substances are formed.

Electrode Potentials

Potentials, E, of half-reactions as reductions versus the standard hydrogen electrode.

Hydrogen

Discovered : by Henry Cavendish in 1766.
Isolated in London, UK.
Origin : The name is derived from the Greek ‘hydro genes’, meaning water forming.
Description :A colourless, odourless gas that burns and can form an explosive mixture with air. It is currently manufactured from methane gas, but is also produced by the electrolysis of water and aqueous salts. The gas is used to make such key materials as ammonia, cyclohexane and methanol, which are intermediates in the production of fertilisers, plastics and pharmaceuticals. Some see hydrogen gas as the clean fuel of the future - generated from water and returning to water when it is oxidised. Hydrogen-powered fuel cells are increasingly being seen as pollution-free sources of energy.

Formula

Combination of symbols that indicates the chemical composition of a substance.

 

Ostwald Process

A process for the industrial production of nitrogen oxide and nitric acid from ammonia and oxygen.

Linkage Isomers

Isomers in which a particular ligand bonds to a metal ion through different donor atoms.

 

Capillary Action

The drawing of a liquid up the inside of a small-bore tube when adhesive forces exceed cohesive forces, or the depression of the surface of the liquid when cohesive forces exceed the adhesive forces.

Element

A substance that cannot be decomposed into simpler substances by chemical means.

Nernst Equation

Corrects standard electrode potentials for nonstandard conditions.

Formula Weight

The mass of one formula unit of a substance in atomic mass units.

 

Spectator Ions

Ions in a solution that do not participate in a chemical reaction.

Essential Oil

A plant extract that has a distinctive odour or flavour.

Crystalline Solid

A solid characterized by a regular, ordered arrangement of particles.

Active Metal

Metal with low ionization energy that loses electrons readily to form cations.

Raoult's Law

The vapor pressure of a solvent in an ideal solution decreases as its mole fraction decreases.