Reaction Order Determiner

Reaction Order Determiner | Online Free Tool | Elysia Tools

Tool usage guide

Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Category: Science & Education
Input types: textarea
Output type: text
Sample coverage: 4
API ready: Yes

Overview

The Reaction Order Determiner calculates individual reaction orders, the overall rate law, and the apparent rate constant from experimental initial-rate data. It supports single-reactant systems using log-log linear regression and two-reactant systems using the classic method of pairs, automatically back-calculating rate constants for each trial.

When to use

Analyzing chemical kinetics lab data where initial reaction rates are measured across varying reactant concentrations.
Determining whether a single-reactant process follows zero, first, second, or fractional order kinetics.
Solving multi-reactant rate law problems using isolation or method of pairs comparison.

How it works

1Enter experimental initial-rate data into the text area with one trial per line, formatting as '[A] rate' for single reactants or '[A] [B] rate' for two reactants.
2For single-reactant sets, the tool runs a least-squares log-log linear regression (ln v₀ = n·ln[A] + ln k) to extract the reactant order and baseline rate constant.
3For two-reactant sets, the tool isolates pairs where one reactant is held constant to determine individual partial orders (n_A and n_B) using logarithmic rate-to-concentration ratios.
4The tool formats the final rate law equation, back-calculates the rate constant k for each individual trial, and outputs the average k value.

Use cases

Undergraduate and high school chemistry students verifying rate law calculations from kinetic laboratory reports.
Chemistry instructors creating and checking problem sets for the method of initial rates.
Chemical researchers estimating empirical reaction orders and rate constants from bench-scale kinetic screening.

Examples

1. Single-Reactant Decomposition

Chemistry Student

Background

A student measures the decomposition rate of nitrogen dioxide at three starting concentrations in a kinetics lab.

Problem

The student needs to determine if NO2 decomposition is first or second order and find the average rate constant.

How to use

Enter the concentration and rate pairs line-by-line into the experiment input field.

0.10 0.02
0.20 0.08
0.40 0.32

Outcome

The tool performs a log-log fit showing order n_A = 2, rate law v = k·[A]^2, and an average k of 2.

2. Two-Reactant Reaction Order Determination

Lab Instructor

Background

An instructor needs to verify exam solution keys for an initial-rate problem involving reactants A and B.

Problem

Calculate individual orders n_A and n_B, overall reaction order, and rate constant k across three experimental runs.

How to use

Paste three trials containing [A], [B], and initial rate values into the tool.

FAQ

What input format does the tool expect?

Enter whitespace-separated values on each line: use two values '[A] rate' for a single reactant, or three values '[A] [B] rate' for two reactants.

Can I use scientific notation for small reaction rates?

Yes, standard scientific notation like 2.0e-3 or 4.0e-4 is fully supported for concentrations and rates.

How does the tool identify integer reaction orders?

Calculated orders within 0.05 of a whole number are recognized as clean integer orders (such as 0, 1, 2, or 3).

How is the rate constant k calculated?

The rate constant k is computed individually for every experiment by substituting measured concentrations and rates into the derived rate law, then averaged across all trials.

What happens if a two-reactant dataset lacks matching pairs?

The two-reactant method requires pairs where one concentration is held constant to isolate individual partial orders.

0.10 0.10 2.0e-3
0.20 0.10 4.0e-3
0.10 0.20 8.0e-3

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Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Overview

When to use

How it works

Use cases

Examples

1. Single-Reactant Decomposition

2. Two-Reactant Reaction Order Determination

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