| oxidation-reduction | A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs. (12 Dec 1998) |
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| oxidation-reduction electrode | An electrode capable of measuring oxidation-reduction potential. See: quinhydrone electrode. Synonym: redox electrode. (05 Mar 2000) |
| oxidation-reduction indicator | A substance that undergoes a definite colour change at a specific oxidation potential. Synonym: redox indicator. (05 Mar 2000) |
| oxidation-reduction potential | <chemistry, physics> The potential in volts of an inert metallic electrode measured in a system of an arbitrarily chosen ratio of [oxidant] to [reductant] and referred to the normal hydrogen electrode at absolute temperature. It is calculated from the following equation: where R is the gas constant expressed in electrical units, T the absolute temperature (Kelvin), n the number of electrons transferred, F the faraday and E0 the normal symbol for the potential of the system at pH 0; for biological systems E0' is often used (in which pH = 7). Compare: Nernst's equation. Synonym: redox potential. (05 Mar 2000) |
| oxidation-reduction reaction | <chemistry> Any reaction in which electrons are removed from one molecule or atom and given to another molecule or atom. (09 Oct 1997) |
| oxidation-reduction system | <enzyme> An enzyme system in the tissues by which oxidation and reduction proceed simultaneously through the transference of hydrogen or of one or more electrons from one metabolite to another. See: oxidation-reduction. Synonym: redox system. (05 Mar 2000) |
| colourimetric titration | A titration in which the end point is marked by a colour change. (05 Mar 2000) |
| whole-body titration curve | A graphic representation of the in vivo changes in hydrogen ion, PaCO2, and bicarbonate which occur in arterial blood in response to primary acid-base disturbances. (05 Mar 2000) |
| potentiometric titration | A titration during which the pH is continually measured with some value of the pH serving as end point. (05 Mar 2000) |
| skin test end-point titration | A quantitative form of intradermal testing for the relative allergenicity of a substance. It is used to determine the amount of an allergen that will be tolerated in immunotherapy. (12 Dec 1998) |
| titration | <chemistry> The act or process of titrating; a substance obtained by titrating. Source: Websters Dictionary (01 Mar 1998) |
| formol titration | A method of titrating the amino groups of amino acids, by adding formaldehyde to the neutral solution; the formaldehyde reacts with the NH3+ group, liberating an equivalent quantity of H+, which may then be estimated by titration with NaOH. (05 Mar 2000) |
| algal oxidation pond | <ecology> A wide, shallow pond used in waste water treatment, the algae produce oxygen so that bacteria can aerobically digest sewage in the water. (09 Oct 1997) |
| alpha-oxidation | A form of oxidation of fatty acids in which carbons are removed one at a time in the form of CO2; the alpha-carbon is first hydroxylated and then converted into a carbonyl; a deficiency of this pathway is associated with Refsum's disease. (05 Mar 2000) |
| auto-oxidation | The direct combination of a substance with molecular oxygen at ordinary temperatures. Synonym: autoxidation. (05 Mar 2000) |