Reaction Speed Calculator

Calculator inputs

Initial concentration, C₀ (mol/L)

Final concentration, C_t (mol/L)

Elapsed time

Time unit

Stoichiometric coefficient, ν

Reaction-order model

Reactor volume (L)

Molecular weight (g/mol)

Forecast time using selected model

Reference rate constant, k_ref

Reference temperature (°C)

Batch temperature (°C)

Activation energy (kJ/mol)

Keep the same concentration and time basis across all inputs. If you use temperature adjustment, provide every Arrhenius field.

Example data table

Batch	C₀ (mol/L)	C_t (mol/L)	Time (min)	Order	Average speed (mol/L/min)	Conversion
R-101	1.20	0.80	10	First	0.0400	33.33%
R-202	0.95	0.50	12	Second	0.0375	47.37%
R-303	2.00	1.10	18	Zero	0.0500	45.00%

Formula used

Average reaction speed

r_avg = (C₀ - C_t) / (ν × t)

Conversion

X = ((C₀ - C_t) / C₀) × 100

Rate constant by reaction order

Zero order: k = (C₀ - C_t) / t

First order: k = ln(C₀ / C_t) / t

Second order: k = (1 / C_t - 1 / C₀) / t

Arrhenius temperature adjustment

k₂ = k₁ × exp[ -(E_a/R) × (1/T₂ - 1/T₁) ]

This calculator assumes a disappearing reactant in batch or reactor analysis. Temperatures are converted to Kelvin internally before Arrhenius evaluation.

How to use this calculator

Enter the initial and final reactant concentrations in the same units.
Provide elapsed time and select the matching time basis.
Set the stoichiometric coefficient for the tracked reactant.
Choose the reaction-order model that best matches your data.
Add reactor volume and molecular weight to estimate moles and mass consumed.
Use forecast time to project future concentration from the selected model.
Fill every Arrhenius field only when you need temperature-adjusted rate constants.
Submit the form, review the result cards, and export CSV or PDF.

FAQs

1. What does reaction speed mean here?

It represents the observed disappearance rate of a reactant from concentration data over time. The tool also estimates model-based kinetics and related engineering outputs.

2. Why do I need a stoichiometric coefficient?

Reaction rate is commonly normalized by stoichiometry. A different coefficient changes the reported average speed for the chosen reactant species.

3. Which reaction order should I choose?

Choose the order that best matches your experimental behavior or known mechanism. If unsure, compare your plant or lab data against each model externally.

4. Can this calculator handle temperature effects?

Yes. Enter a reference rate constant, reference temperature, batch temperature, and activation energy to estimate a temperature-adjusted rate constant using Arrhenius behavior.

5. What units should I use?

Use consistent concentration, time, volume, and molecular-weight units throughout. The calculator reports results directly from that selected basis.

6. Why is final concentration limited?

This page models disappearance of a tracked reactant. For that case, final concentration should not exceed the starting concentration during the measured interval.

7. What does forecast concentration use?

Forecasting uses the temperature-adjusted rate constant when available. Otherwise, it uses the rate constant estimated from your entered concentration data and reaction order.

8. Can I use this for production reports?

Yes. The results section includes practical values such as conversion, consumed mass, productivity, and export tools for documentation or review meetings.