Balancing Chemical Equations - Online Game

Balance chemical equations with Cali. In a chemical reaction, atoms are never created or destroyed, so every element must have the same number of atoms on both sides of the arrow. Change the numbers in front of the formulas (the coefficients) with the arrows or the keyboard and watch the molecules and the atom counts change. Start with Practice – six reactions with live atom counts – and then play the Game: 3 levels of 5 equations each, from making water to equations with brackets. Your best results are saved in this browser.

How to balance a chemical equation

1. Count the atoms of every element on the left side and on the right side.
2. Change only the coefficients, the big numbers in front of the formulas. Never change the small subscripts: H₂O₂ is a different substance from H₂O.
3. Balance one element at a time. It is easiest to start with an element that is in only one formula on each side; hydrogen and oxygen are often easiest to leave for last.
4. Count all the atoms again. If every coefficient can be divided by the same number, divide them, so that the numbers are as small as possible.

Example: H₂ + O₂ → H₂O. There are 2 oxygen atoms on the left and only 1 on the right, so put 2 in front of H₂O. Now there are 4 hydrogen atoms on the right and 2 on the left, so put 2 in front of H₂: 2H₂ + O₂ → 2H₂O. Each side has 4 H atoms and 2 O atoms.