Acidic dissociation constant.
Most of the substances are acidic in water are actually weak acid. The extent to which an acid ionizes in ionization reaction. In general, we can represent any acid by this symbol HX, where X- is the formula for the conjugate base that remains when the proton ionizes. The ionization equilibrium is then given by the equation.
HX (aq) = H+(aq) + X-(aq)
The corresponding equilibrium constant is expresses as:
Ka = [H+][X‑]/[HX]
Where Ka is called the acid-dissociation constant.

Acrilan.
A name for a synthetic fibre, based on a copolymer of acrylonitrile with minor proportions of other unspecified vinyl monomers.

Acrylate.
CH₂=CHCOOR. Here R is an alkyl radical such as CH₃, C₂H₅, an ester of acrylic acid. Easy to polymerize. It finds use in the production of polymers.

Acrylic acid.
Ch₂=CH-COOH. Refers to the simplest monobasic olefinic acid. It is colourless liquid. It is soluble in water.

Acrylonitirle.
The elements ectinium, thorium protactinium, uranium, neptunium, plutonium, americium, curium, berekelium, californium, einsteinium, fermium, mendelevium, nobelium, and lawrencium are collectively known as actinides.