Dictionary of Chemistry [6th Ed.]

small quantities in cells on a plate,

and properties are investigated by

some automated technique. It is par-

ticularly used in the development of

new drugs.

combustionA chemical reaction

in which a substance reacts rapidly

with oxygen with the production of

heat and light. Such reactions are

often free-radical chain reactions,

which can usually be summarized as

the oxidation of carbon to form its

oxides and the oxidation of hydrogen

to form water. See also flame.

commensurate latticeA lattice

that can be divided into two or more

sublattices, with the basis vectors of

the lattice being a rational multiple

of the basis vectors of the sublattice.

The phase transition between a com-

mensurate lattice and an incommen-

surate lattice can be analysed using

the Frenkel–Kontorowa model. An

ion that is common to two or more

components in a mixture. In a solu-

tion of XCl, for example, the addition

of another chloride YCl, may precipi-

tate XCl because the solubility prod-

uct is exceeded as a result of the

extra concentration of Cl

_

ions. This

is an example of a common-ion

effect.

common saltSee sodium

chloride.

competitive inhibitionSee inhi-

bition.

combustion 136

c

octahedral square-planar

tetrahedral trigonal-bipyramid

Complexes