# pseudo first order

pseudo first order
First-order First`-or"der, a. decaying at an exponential rate; -- a mathematical concept applied to various types of decay, such as radioactivity and chemical reactions.

Note: In first order decay, the amount of material decaying in a given period of time is directly proportional to the amount of material remaining. This may be expressed by the differential equation: dA/dt = -kt where dA/dt is the rate per unit time at which the quantity (or concentration) of material (expressed as A) is increasing, t is the time, and k is a constant. The minus sign in front of the "kt" assures that the amount of material remaining will be decreasing as time progresses. A solution of the differential equation to give the quantity A shows that: A = e^{-kt} where e is the base for natural logarithms. Thus this type of decay is called exponential decay. In certain chemical reactions that are in fact second-order, involving two reactants, the conditions may be chosen in some cases so that one reactant is vastly in excess of the other, and its concentration changes very little in the course of the reaction, so that the reaction rate will be approximately first order in the more dilute reactant; such reactions are called {pseudo first order}. [PJC]

The Collaborative International Dictionary of English. 2000.

### Look at other dictionaries:

• First-order — First or der, a. decaying at an exponential rate; a mathematical concept applied to various types of decay, such as radioactivity and chemical reactions. Note: In first order decay, the amount of material decaying in a given period of time is… …   The Collaborative International Dictionary of English

• Order of reaction — In chemical kinetics, the order of reaction with respect to certain reactant, is defined as the power to which its concentration term in the rate equation is raised [1]. For example, given a chemical reaction 2A + B → C with a rate equation r =… …   Wikipedia

• order — 1. In biologic classification, the division just below the class (or subclass) and above the family. 2. In a reaction, o. is the sum of the exponents of all the concentration terms in that reaction s rate expression. For example, for the natural… …   Medical dictionary

• Pseudo-Dionysius the Areopagite — Full name Pseudo Dionysius the Areopagite Other names Pseudo Dionysius , Pseudo Denys , mistakenly identified as Dionysius the Areopagite Born unknown, 5th to 6th century AD Died unknown, 5th to 6th century AD Era Ancient philosop …   Wikipedia

• Pseudo amino acid composition — Pseudo amino acid composition, or PseAA composition, was originally introduced by [http://gordonlifescience.org/members/kcchou/index.html Professor Kuo Chen Chou] [1] in 2001 to represent protein samples for statistical prediction. In contrast… …   Wikipedia

• Pseudo-anglicism — Pseudo anglicisms are words in languages other than English which were borrowed from English but are used in a way native English speakers would not readily recognize or understand. Pseudo anglicisms often take the form of portmanteau words,… …   Wikipedia

• Pseudo-Geber — ( false Geber ) is the name assigned by modern scholars to an alchemist born in the 13th century, probably Paul of Taranto [Insuments and Experimentation in the History of Chemistry ;Fredric L Holmes and Trevor H Levere;MIT Press 2000 ISBN… …   Wikipedia

• Pseudo-differential operator — In mathematical analysis a pseudo differential operator is an extension of the concept of differential operator. Pseudo differential operators are used extensively in the theory of partial differential equations and quantum field theory.… …   Wikipedia

• Pseudo-order — In constructive mathematics, a pseudo order is a constructive generalisation of a linear order to the continuous case. The usual trichotomy law does not hold in the constructive continuum because of its indecomposability, so this condition is… …   Wikipedia

• Pseudo-Doku — Der Dokumentarfilm ist eine Filmgattung, die sich mit tatsächlichem Geschehen befasst. Im Gegensatz zum Spielfilm geschieht dies in der Regel ohne bezahlte Darsteller. Es gibt eine große Bandbreite von verschiedenen Dokumentarfilmarten, die sich… …   Deutsch Wikipedia