Zero-Order Reaction Calculator

In a zero-order reaction, the reaction rate stays constant regardless of reactant concentration — a behavior seen in enzyme-catalyzed processes and some drug metabolism pathways. Enter your Initial Concentration [A₀], Rate Constant (k), and Time (t) into the Zero-Order Reaction Calculator, then select what to Calculate — final concentration, rate constant, half-life, or time to zero concentration. Secondary outputs include the constant Reaction Rate and Percent Reacted at the given time. Also try the calculate Van't Hoff Factor van't Hoff Factor (i).

mol/L

Initial concentration of reactant A

mol/L·s

Rate constant for zero-order reaction

s

Time elapsed since reaction start

Results

Result

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Reaction Rate

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Percent Reacted

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Results Table

Frequently Asked Questions

What is a zero-order reaction?

A zero-order reaction is one where the reaction rate is independent of the concentration of the reactant. The rate remains constant throughout the reaction until the reactant is completely consumed. See also our calculate Cell Potential, E, Temperature (Kelvin) & RT/nF Factor — Nernst Equation.

How do you calculate the rate constant for a zero-order reaction?

For zero-order reactions, the rate constant k can be calculated using the integrated rate equation: [A] = [A₀] - kt. Rearranging gives k = ([A₀] - [A]) / t, where k has units of mol/L·s.

What is the half-life of a zero-order reaction?

The half-life of a zero-order reaction is t₁/₂ = [A₀] / (2k). Unlike first-order reactions, the half-life depends on the initial concentration and increases as the reaction progresses. You might also find our Half-Life Calculator (Chemical) useful.

How does zero-order kinetics differ from first-order kinetics?

In zero-order kinetics, the rate is constant and independent of concentration, while in first-order kinetics, the rate is proportional to the concentration. Zero-order reactions show linear concentration decrease over time.

What are examples of zero-order reactions?

Common examples include enzyme-catalyzed reactions at saturating substrate concentrations, surface-catalyzed reactions where the surface is fully occupied, and some photochemical reactions where light intensity is the limiting factor.

When does a zero-order reaction end?

A zero-order reaction continues at a constant rate until one of the reactants is completely consumed. The time for complete consumption is t = [A₀] / k, after which the reaction stops abruptly.