Balancing Chemical Equations
A chemical equation describes the changes that occur during a chemical reaction. The equation shows the reactants on the left hand side and the products on the right hand side of the arrow. Balancing a chemical equation is a mathematical approach used in chemistry to establish the relationship between the quantity of reactants and products.
To balance chemical equations, the following three steps are used:
Write the unbalanced equation: using chemical nomenclature (see the Periodic Table of Elements), write out the reactants on the left hand side of the equation. Remember to use uppercase and lowercase letters, where appropriate. Draw an arrow to represent "forms to react". The direction of the arrow indicates the flow of the reaction. Finally, write out the products on the right hand side of the equation using chemical nomenclature.
Balance the equation: use the Law of Conservation of Mass to balance, or achieve the same number of atoms of every element on each side of the equation.
Identify the states of matter: use the following subscripts for the compounds: (g) for gaseous substances, (s) for solids, (l) for liquids, and (aq) for aqueous solutions.
In the following examples, you will be given the chemical equations and states. You are responsible for balancing them.
Type integer coefficients in front of the reactants and products to balance the chemical equations. Use the smallest integers that work. If no coefficients are required to balance the equation, simply place the integer 1 in front of each reactant and/or product.
Click "Check" to see whether your response below is the correct balanced chemical equation.
1. Cus+O2g → CuOs
2. H2Ol → H2g+O2g
3. Fes+H2Og → H2g+Fe3O4g
4. AsCl3aq+H2Saq → As2S3s+HClaq
5. Fe2O3s+H2g → Fes+H2Ol
6. CaCO3s→ CaOs+CO2g
2 Cus+1 O2g → 2 CuOs
2 H2Ol → 2 H2g+1 O2g
3 Fes+4 H2Og → 4 H2g+1 Fe3O4g
2 AsCl3aq+3 H2S(aq → 1 As2S3s+6 HClaq
1 Fe2O3s+3 H2g → 2 Fes+3 H2Ol
1 CaCO3s → 1 CaOs+1 CO2g
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