First-order rate law

The First-order Rate Law  calculator computes the reaction rate of concentration change of a substance based on a Rate Law equation, the initial concentration (A₀) and the rate constant (k) .

INSTRUCTIONS: Choose the preferred units and enter the following:

• [A₀] Initial Concentration of Substance
• (k) The rate constant

Reaction Rate: The calculator returns the rate of reaction of the substance moles per liter per second (mol/(L*s) ).  

Chemistry Rate Law Calculators

• Zero Order Rate Law (Integral form)
• Zero Order  Half Life
• Zero Order Rate Law
• First Order Rate Law (Integral form)
• First Order Half Life
• First Order Rate Law
• Second Order Rate Law (Integral form)
• Second Order Half Life
• Second Order Rate Law

The Science

The first-order rate law equation^[1] calculates the rate at which the products get converted to reactants, such that the rate depends on a concentration of only one reactant. The equation shown above is the differential^[3] form of the first-order rate equation, which describes the rate on a molecular level and shows how the rate depends on the concentration of the reactants. Recall that rate in a differential form is d/dt and can be integrated. You can find a full integration of the first-order rate law here.

The Math

The equation is

Rate=k[A]¹=k[A] ^[2]

where

• Rate is the rate of the first order reaction in units of (Molarity/time)
• k is the rate constant of the reaction in units (1/time)
• [A] is the concentration of the reactants in units of (mol/L)

Related Topics

• First-order (Integral form)
• First-order half-life
• Rate law calculator

Supplement Material

• Khan Academy: Rate law and reaction order
• Rate and Order of Reactions

References

[1]https://en.wikipedia.org/wiki/Rate_equation

[2]Whitten, et al. 10th Edition. Pp. 626,629,631

[3]https://en.wikipedia.org/wiki/Differential_equation

[Picture] http://chemwiki.ucdavis.edu/Core/Physical_Chemistry/Kinetics/Reaction_Rates/First-Order_Reactions