Rate Equation - First-order Reactions

First-order Reactions

See also: Order of reaction

A first-order reaction depends on the concentration of only one reactant (a unimolecular reaction). Other reactants can be present, but each will be zero-order. The rate law for an elementary reaction that is first order with respect to a reactant A is

k is the first order rate constant, which has units of 1/s.

The integrated first-order rate law is

A plot of vs. time t gives a straight line with a slope of .

The half-life of a first-order reaction is independent of the starting concentration and is given by .

Examples of reactions that are first-order with respect to the reactant:

Read more about this topic:  Rate Equation

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