1. Start by identifying the unbalanced equation. This is an equation where the number of atoms of each element is not the same on both sides.
2. Choose one element to start balancing. This is usually the element that appears in the most compounds.
3. Balance the number of atoms of the chosen element by adding coefficients in front of the compounds that contain it. Coefficients represent the relative number of molecules or moles of each compound involved in the reaction.
4. Check the number of atoms of other elements in the equation. If any element is unbalanced, adjust the coefficients of the compounds that contain it until the equation is balanced.
5. Repeat steps 3 and 4 until all elements are balanced.
Here's an example of how to balance the equation for the combustion of methane:
CH₄ + O₂ → CO₂ + H₂O
Initially, we have 1 carbon atom on the left side and 1 carbon atom on the right side, which is balanced. However, we have 4 hydrogen atoms on the left side and only 2 hydrogen atoms on the right side, so we need to balance hydrogen. To do this, we can add a coefficient of 2 in front of H₂O:
CH₄ + O₂ → CO₂ + 2H₂O
Now we have 4 hydrogen atoms on both sides. Let's check oxygen atoms. We have 2 oxygen atoms on the left side and 3 oxygen atoms on the right side, so we need to balance oxygen. We can do this by adding a coefficient of 2 in front of O₂:
CH₄ + 2O₂ → CO₂ + 2H₂O
Now we have 4 oxygen atoms on both sides. Finally, let's check carbon atoms again. We have 1 carbon atom on both sides, so the equation is balanced.
Therefore, the balanced equation for the combustion of methane is:
CH₄ + 2O₂ → CO₂ + 2H₂O
Remember that when balancing an equation, you can only change the coefficients in front of the compounds. You cannot change the subscripts, as this would change the chemical identity of the compounds.
