Dictionary, Defintion, Meaning, What is Activated Molecule, Acyloin Condensation, Activated Adsorption, Activation Analysis, Active Carbon, Active Mass, Active Transport, Anold Terminology

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Home >> Chemistry Dictionary >>Activated Molecule - Acyloin Condensation

Your Ad Here	Activated adsorption. Chemisorption often has an activation energy associated with it and is sometimes referred as activated adsorption. Activated molecule. Molecules will only react on collision when they posses more than a certain minimum amount of energy. A molecule which has acquired more energy than the average amount possessed by other molecules, and is in a more reactive condition, is said to be activated. Molecules are activated when they absorb a quantum of light, or when they come in contact with a hot surface. Activation analysis. An analytical technique in which an artificial radioactive isotope is formed by irradiation from the stable element to be determined and the amount of the artificial isotope is then estimate from its radioactivity.
Active carbon. Carbon (charcoal) treated at high temperature with steam, air or CO₂. Used as an absorbent for removal of small traces of impurities from a gas or liquid. Used extensively in water and waste water treatment, air pollution control, as a catalyst, sugar refining, purification of chemicals and gases (gas masks), dry cleaning, rubber reclamation, cigarette filters. Active centres. In heterogeneous catalysis adsorption is considered to accar at active centres on the surface of the catalyst. Active mass. The thermodynamics activity. Anold terminology.
Active series. The metals are arranged in order of their ease of oxidation. Such a list is known as active series. The metals on the top are those that are most easily oxidized are whose ions are correspondingly most difficult to reduce. These are active metals. Active series hydrogen and some metals. ® Metals easily oxidized. Metals K Ca Na Mf Al Zn Fe Ni Sn Pb H2 Cu Ag Au Ion K⁺ Ca⁺ Na⁺ Mg⁺ Al⁴⁺ Zn²⁺ Fe²⁺ M²⁺ Sn⁺ Pb²⁺ H⁺ Cu²⁺ Ag^- Au²⁺ ®Most easily oxidized® The active serried indicate not only the reactivities of metals with acids but also their reactivities with each other.	Your Ad Here
See what happens when a piece of zinc is placed in contact with a solution of Cu²⁺. The blue colour that is characteristic of Cu²⁺ ions in aqueous solution fades and copper metals begin to settle on the zinc. At the same time, the zinc begins to dissolve. These changes are shown by the equation: Zn(s) Cu²⁺ (aq.)-----> Zn²⁺ (aq.) + Cu(s) The position of copper in the activity serried indicated that it has a stronger attraction for electrons than does zinc because it is more easily reduced. Consequently, copper would end up with electrons. In any oxidation-reduction between a metal and a metal ions, the more active will end up in the oxidize state.
Your Ad Here	Active transport. The biochemical transport of substances, usually against a concentration gradient, other than by osomosis or diffusion. Activity. A thermodynamics quantity which measures the effective concentration or intensity of a particular substances in a given chemical system. The absolute activity, a°, of the substances is given by μ=RT in a°, where μ is the chemical potential of the substances, R is the gas constant. T the absolute temperature. The relative activity, a is given by μ=μ° +RT in a:μ° being the chemical potential of the substances in its standard state. For dilute, ideal solutions the activity is directly proportional to the concentration, for ideal gases, activity is proportional to the partial pressure of the gas.

Activity coefficient.
(f or y) A dimensionless factor by which the concentration (c) of a substances must be multiplied to give and exact measure of its thermodynamics activity (a) in a chemical system, i.e. a = fc. It is a measure of the deviation from ideal behaviour of the solution; f is unity for an ideal mixture and greater or less than unity for a non-ideal system. Activity coefficients of electrolytes are considered to be the geometrical mean of the single ion activities, the latter being hypothetical quantities which cannot be determined separately.

Actomyosin.
The most important protein of muscle.

Acyclic.
Containing chains, possibly with branches but no rings.

Acyclic compounds.
Organic compounds having open chains where all atoms get with each other to form simple or branched structures.

Acyl.
The general name for organic acid groups, which are the residues of carboxylic acids after removal of the OH group.

Acylation.
A chemical transformation which substitutes the acyl (RCO-) group into a molecule, generally for an active hydrogen of e.g. an OH- group.

Acyloin condensation.
The formation of an acyolin, very often cyclic by condensation two molecules of ester with sodium.

Acyloins.
1, 2-Ketoalcohols of the type R-CO-CHR.OH. See acetoin, benzoin.

Adams catalyst.
P₁O₂nH₂O. Produced by fusion of H₂P₁Cl₆ with sodium nitrate at 500-550°C and leaching of the cooled melt with water. Stable in air activated by hydrogen.

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