Balancing Chemical Equations for beginners

Steps in Balancing a Chemical Equation

Balancing a chemical equation involves a certain amount of trial and error. In general, however, you should follow these steps:

1. Count each type of atom in reactants and products. Does the same number of each atom appear on both sides of the arrow? If not, the equation is not balanced, and you need to go to step 2.
2. Place coefficients, as needed, in front of the symbols or formulas to increase the number of atoms or molecules of the substances. Use the smallest coefficients possible. Warning! Never change the subscripts in chemical formulas. Changing subscripts changes the substances involved in the reaction. Change only the coefficients.
3. Repeat steps 1 and 2 until the equation is balanced.

Q: Balance this chemical equation for the reaction in which nitrogen (N₂) and hydrogen (H₂) combine to form ammonia (NH₃):N₂ + H₂ → NH₃

A: First count the nitrogen atoms on both sides of the arrow. There are two nitrogen atoms in the reactants so there must be two in the products as well. Place the coefficient 2 in front of NH₃ to balance nitrogen:N₂ + H₂ → 2 NH₃

Now count the hydrogen atoms on both sides of the arrow. There are six hydrogen atoms in the products so there must also be six in the reactants. Place the coefficient 3 in front of H₂ to balance hydrogen:N₂ + 3 H₂ → 2 NH₃

Summary

• A chemical equation represents the changes that occur during a chemical reaction. It has the general form: Reactants → Products. All chemical equations must be balanced. This means that there must be the same number of each type of atom on both sides of the arrow.
• Coefficients are used to balance chemical equations. A coefficient is a number placed in front of a chemical symbol or formula. It shows how many atoms or molecules of the substance are involved in the reaction.
• To balance a chemical equation, place coefficients as needed in front of the symbols or formulas so the same number of each type of atom occurs in both reactants and products.

• oxidation = loss of electrons
• reduction = gain of electrons
• reducing agent = species that is oxidized
• oxidizing agent = species that is reduced