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First Order Reaction Concentration Calculator

Use this online first order reaction concentration calculator with labeled inputs and a worked example. [A]t = [A]₀ exp(−kt); t½ = ln 2/k.

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first order kinetics calculator online

Use first order reaction concentration calculator online with the chemical quantities shown below. Irreversible first-order disappearance at constant rate constant.

How to use it

Enter Initial concentration (mol/L). Set First-order rate constant (s⁻¹), Elapsed time (s). Select Calculate, check the result units, then copy or download the JSON result.

Options and example settings

OptionChoices / valueExample default
Initial concentration (mol/L)Main input. Decimal or scientific notation. Zero or positive values. 1
First-order rate constant (s⁻¹)Option. Decimal or scientific notation. Positive values only. 0.1
Elapsed time (s)Option. Decimal or scientific notation. Zero or positive values. 10

Calculation method

[A]t = [A]₀ exp(−kt); t½ = ln 2/k

Worked examples

Worked case for first order reaction concentration calculator. Irreversible first-order disappearance at constant rate constant.

First Order Reaction Concentration Calculator — example with explicit inputs

Settings: First-order rate constant (s⁻¹): 0.1; Elapsed time (s): 10

Input:

1

Expected result for the example input and options:

Output:

{
  "concentration_mol_L": 0.36787944117144233,
  "half_life_s": 6.931471805599452
}

Limitations and common mistakes

  • Irreversible first-order disappearance at constant rate constant.
  • Match every input to its displayed unit; scientific notation such as 1e-6 is accepted.
  • Check substance identity, reaction coefficients and concentration conventions. Numerical output does not verify experimental conditions.

Frequently asked questions

How can I use first order kinetics calculator online?

Enter Initial concentration (mol/L). Set First-order rate constant (s⁻¹), Elapsed time (s). Select Calculate, check the result units, then copy or download the JSON result.

Which model does First Order Reaction Concentration Calculator use?

[A]t = [A]₀ exp(−kt); t½ = ln 2/k. Irreversible first-order disappearance at constant rate constant.

Technical references

Where is my input processed?

The bundled tool processes input in your browser. It does not upload tool input to a conversion service. Other site plugins, analytics, advertising and browser extensions may have separate behavior.

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