rxnkinetics 1.0.0

A Python CLI toolkit for chemical reaction kinetics analysis

rxnkinetics

A Python CLI toolkit for chemical reaction kinetics analysis. Solve rate equations, fit experimental data, determine reaction orders, and perform Arrhenius analysis — all from the command line.

Features

Command	Description
solve	Simulate concentration–time profiles by solving d[X]/dt = −k[X]ⁿ numerically
fit	Determine the rate constant k from experimental data via nonlinear least-squares fitting
order	Test multiple candidate orders and rank by R² to identify the best-fit reaction order
halflife	Calculate t₁/₂ for any reaction order (0, 1, 2, fractional)
arrhenius	Compute activation energy Eₐ and pre-exponential factor A from temperature-dependent rate data
gasfit	Analyze gas evolution kinetics — estimate V∞ and extract k via linearization

Installation

git clone https://github.com/emreyilmazcode/ReactionKinetics.git
cd ReactionKinetics
pip install -e .

After installation, rxnkinetics is available as a command:

rxnkinetics solve --order 1 --x0 1.0 --k 0.1 --t 50

Or run directly without installing:

python -m rxnkinetics.cli solve --order 1 --x0 1.0 --k 0.1 --t 50

Quick Start

Simulate a first-order decay

rxnkinetics solve --order 1 --x0 1.0 --k 0.1 --t 50

============================================
  REACTION KINETICS SIMULATION
============================================
  Reaction Order   : 1.0
  Initial [X]₀     : 1.0 M
  Rate Constant k  : 0.1
  Time Elapsed     : 50.0 s
--------------------------------------------
  → Remaining [X]  : 0.006738 M
  → Conversion     : 99.33 %
============================================

Fit rate constant from experimental data

rxnkinetics fit --file examples/first_order.csv --order 1

Determine reaction order automatically

rxnkinetics order --file examples/first_order.csv --plot

Calculate half-life

rxnkinetics halflife --order 1 --k 0.1
rxnkinetics halflife --order 2 --k 0.05 --x0 1.0

Arrhenius analysis

rxnkinetics arrhenius --file examples/arrhenius.csv

Gas volume kinetics

rxnkinetics gasfit --file examples/gas_volume.csv

Input Data Format

All commands expecting a --file argument use two-column CSV files:

Command	Column 1	Column 2
fit, order	Time (s)	Concentration (M)
arrhenius	Temperature (K)	Rate constant (k)
gasfit	Time	Volume (mL)

Header rows are automatically detected and skipped.

Theory

Rate Law Integration

The tool numerically integrates the general rate law:

$$\frac{d[X]}{dt} = -k[X]^n$$

using scipy.integrate.odeint. Rate constant fitting uses scipy.optimize.curve_fit with the ODE solution as the model function.

Arrhenius Equation

Temperature dependence is analyzed via the linearized Arrhenius equation:

$$\ln k = \ln A - \frac{E_a}{RT}$$

A linear regression of ln(k) vs 1/T yields the activation energy Eₐ and pre-exponential factor A.

Half-Life Expressions

Order	t₁/₂
0	[X]₀ / 2k
1	ln(2) / k
2	1 / (k[X]₀)
n	(2ⁿ⁻¹ − 1) / [k(n−1)[X]₀ⁿ⁻¹]

Project Structure

ReactionKinetics/
├── rxnkinetics/
│   ├── __init__.py      # Package metadata
│   ├── core.py          # ODE solver, fitting, analysis functions
│   ├── cli.py           # Command-line interface
│   └── plotting.py      # Matplotlib visualization
├── examples/            # Sample CSV datasets
├── tests/               # Unit tests
├── setup.py             # Package configuration
├── requirements.txt
├── LICENSE
└── README.md

Running Tests

pip install pytest
pytest tests/ -v

Requirements

• Python ≥ 3.8
• NumPy ≥ 1.20
• SciPy ≥ 1.7
• Matplotlib ≥ 3.4

License

MIT