equation-balancer

Equation balancer

A very simple CLI chemical equation balancer

Install

npm install -g equation-balancer

Requires Node 8.

Usage

Call equation-solver with no arguments to get a loop that prompts for an equation:

balance > Fe + H2SO4 -> Fe2(SO4)3 + H2
2, 3, 1, 3

or call equation-solver with a single argument of the equation you want balanced in quotes.

equation-balancer "Fe + H2SO4 -> Fe2(SO4)3 + H2"
2, 3, 1, 3

Separate terms with + and use -> to separate the reactants from the products. Capitalization matters.

Library

You can also use the function programmatically,

const balance = require('equation-balancer/balance');
balance('Fe + H2SO4 -> Fe2(SO4)3 + H2') // [2, 3, 1, 3]

How does it work?

It parses the input into a set of terms and places them into a matrix.

For example, the equation

Fe + H2SO4 -> Fe2(SO4)3 + H2

Gets parsed into:

const matrix = [
  [ 1, 0, -2, 0 ],    // Fe 
  [ 0, 4, -12, 0 ],   // O
  [ 0, 2, 0, -2 ],    // H
  [ 0, 1, -3, 0 ],    // S
];

And then that gets row reduced into:

const reduceMatrix = [
  [ 1, 0, 0, -0.6666666666666666 ],
  [ 0, 1, 0, -1 ],
  [ 0, 0, 1, -0.3333333333333333 ],
  [ 0, 0, 0, 0 ]
];

The last column of rows in the matrix get converted to fractions and then the LCM is applied to give the final result:

2, 3, 1, 3