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What does this calculator estimate?
A reaction rate calculator applies the rate law. Enter the rate constant, concentrations, and experimental orders to find the reaction rate.
- rate = k[A]^x[B]^y
- Orders come from experiment, not the equation
- Units of k depend on the overall order
What the rate law is
The rate law links reaction speed to reactant concentrations through the rate constant k and the orders x, y. Orders are determined experimentally — they often differ from the balanced coefficients. The tool evaluates the law for your values.
Limitations to watch for
Orders must come from data, not stoichiometry. The tool assumes a simple power-law form — more complex mechanisms (inhibition, saturation) don't fit. k is temperature-dependent (Arrhenius equation).
How to use it in practice
Determine the orders from experiments (method of initial rates) before using the calculator. Use the computed rate to size reaction time or compare conditions. Adjust k for temperature using the Arrhenius equation when needed.
['Enter the rate constant k.', "Enter each reactant's concentration and its experimental order.", 'The tool computes rate = k[A]^x[B]^y.']
What reaction rate is
Reaction rate measures how fast reactants convert to products: rate = change in concentration ÷ time. The calculator supports the basic rate formula and rate constant applications.
Factors that change rate
Concentration, temperature, surface area, catalysts, and pressure all affect how fast reactions proceed. The calculator models the concentration-time relationship; the other factors are context.
A worked example
A reactant falling from 0.50 M to 0.30 M in 40 seconds: average rate = 0.20 ÷ 40 = 0.005 M/s. The calculator returns the rate from the concentration change and time.
Rate laws
For a reaction rate = k[A]^n, the rate constant k and order n define the dependence. The calculator's basic mode handles average rate; rate-law work extends it.
Temperature's exponential effect
Rates roughly double per 10°C rise (Arrhenius behavior). The calculator's snapshot rate is a moment in that curve — temperature context matters for interpretation.
How this calculator works
Formula
Rate law: rate = k × [A]^x × [B]^y, where k is the rate constant, [A] and [B] are reactant concentrations, and x, y are the reaction orders (from experiment, not necessarily the coefficients).
Worked example
With k = 0.05, [A] = 2.0 M, order x = 2: rate = 0.05 × 2.0² = 0.20 M/s. Adding [B] = 1.5 M with order y = 1: rate = 0.30 M/s.
Assumptions to verify
- The reaction follows a simple power-law rate expression.
- Orders and k are known from experiments.
- Temperature is fixed.
Frequently asked questions
What is the rate law?
rate = k[A]^x[B]^y — how reaction speed depends on reactant concentrations, the rate constant, and the reaction orders.
What is the rate constant k?
A temperature-dependent proportionality constant that reflects how fast the reaction proceeds at a given temperature.
Are the orders the same as the coefficients?
No — orders come from experiments and often differ from the balanced equation's coefficients.
How are orders determined?
The method of initial rates: run the reaction with different concentrations and compare how the rate changes.
What are the units of k?
They depend on the overall order: for first order s⁻¹, second order M⁻¹·s⁻¹, zero order M·s⁻¹.
How does temperature affect rate?
k increases with temperature (roughly doubling per 10°C for many reactions), described by the Arrhenius equation.
What is a zero-order reaction?
Rate = k regardless of concentration — common for enzyme-saturated or surface-catalyzed reactions.
What is reaction rate?
The change in concentration per unit time — how fast a reaction proceeds.
How do I calculate it?
Δconcentration ÷ time: 0.20 M ÷ 40 s = 0.005 M/s.
What speeds up reactions?
Higher concentration, temperature, surface area, and catalysts.
What is a rate law?
rate = k[A]^n — how concentration and the rate constant drive the rate.
Cite this tool
BoringToolsKit. “Reaction Rate Calculator.” boringtoolskit.com/reaction-rate-calculator/ (reviewed 2026-08-25). Free to reference in articles, syllabi, and answer posts with a link.
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