Enter your Reaction Rate, Concentrations [A] and [B], and their respective reaction orders (m and n) to calculate the Rate Constant (k) — the Rate Law Calculator also gives you the Rate Law Expression, Overall Reaction Order, and Half-Life based on your chosen Calculation Method.
Rate Constant (k)
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Rate Law Expression
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Half-Life
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Overall Reaction Order
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For experimental data, use the rate law equation: rate = k[A]^m[B]^n. Rearrange to solve for k: k = rate / ([A]^m × [B]^n). Enter your measured rate and concentrations along with the reaction orders to calculate k.
Zero-order: Rate is independent of concentration. First-order: Rate is proportional to concentration. Second-order: Rate is proportional to concentration squared. Each has different integrated rate laws and half-life expressions.
The reaction order is determined experimentally by measuring how the rate changes with concentration. Plot concentration vs time data and analyze the linearity of different transforms (ln[A] vs t for first-order, 1/[A] vs t for second-order).
The rate constant depends primarily on temperature (Arrhenius equation), the presence of catalysts, and the activation energy of the reaction. It's independent of concentration but increases exponentially with temperature.
For first-order reactions: t₁/₂ = ln(2)/k. For second-order: t₁/₂ = 1/(k[A]₀). For zero-order: t₁/₂ = [A]₀/(2k). The relationship varies with reaction order.
This calculator is designed for elementary reactions or reactions that follow simple rate laws. For complex mechanisms, you'll need to determine the rate-determining step and its corresponding rate law first.