Balancing Chemical Equations Worksheet​

Balancing chemical equations might seem tricky at first, but with a little practice, you’ll get the hang of it! This worksheet will help you understand the basics of balancing equations so you can master it step by step.

What is a Chemical Equation?

A chemical equation shows what happens during a chemical reaction. It has:

• Reactants: The starting substances.
• Products: The new substances formed.

Example:
H₂ + O₂ → H₂O

Why Do We Balance Equations?

• Atoms cannot be created or destroyed (Law of Conservation of Mass).
• The number of atoms for each element must be the same on both sides of the equation.

Steps to Balance a Chemical Equation

1. Write the unbalanced equation. Example: H₂ + O₂ → H₂O
2. Count the atoms for each element on both sides.
   • Left: H = 2, O = 2
   • Right: H = 2, O = 1
3. Add coefficients (numbers in front of molecules) to balance.
   • To balance O, place a 2 in front of H₂O: H₂ + O₂ → 2H₂O
   • Now, adjust H by placing a 2 in front of H₂: 2H₂ + O₂ → 2H₂O
4. Check your work!
   • Left: H = 4, O = 2
   • Right: H = 4, O = 2
5. All balanced!

Worksheet 1 : Balance These Equations

1. H₂ + O₂ → H₂O
2. N₂ + H₂ → NH₃
3. Fe + O₂ → Fe₂O₃
4. CH₄ + O₂ → CO₂ + H₂O
5. Al + O₂ → Al₂O₃
6. C₃H₈ + O₂ → CO₂ + H₂O
7. KClO₃ → KCl + O₂
8. Mg + HCl → MgCl₂ + H₂
9. Ca(OH)₂ + HCl → CaCl₂ + H₂O
10. Na + H₂O → NaOH + H₂

Worksheet 1 : Balance These Equations – Solutions

7. H₂ + O₂ → H₂O
   • Step 1: Balance O by adding a 2 in front of H₂O: H₂ + O₂ → 2H₂O
   • Step 2: Balance H by adding a 2 in front of H₂: 2H₂ + O₂ → 2H₂O

   Balanced Equation: 2H₂ + O₂ → 2H₂O

8. N₂ + H₂ → NH₃
   • Step 1: Balance N (already balanced).
   • Step 2: Balance H by adding a 3 in front of H₂ and a 2 in front of NH₃: N₂ + 3H₂ → 2NH₃

   Balanced Equation: N₂ + 3H₂ → 2NH₃

9. Fe + O₂ → Fe₂O₃
   • Step 1: Balance Fe by adding a 4 in front of Fe: 4Fe + O₂ → 2Fe₂O₃
   • Step 2: Balance O by adding a 3 in front of O₂: 4Fe + 3O₂ → 2Fe₂O₃

   Balanced Equation: 4Fe + 3O₂ → 2Fe₂O₃

10. CH₄ + O₂ → CO₂ + H₂O
    • Step 1: Balance C by adding a 1 in front of CO₂: CH₄ + O₂ → CO₂ + H₂O
    • Step 2: Balance H by adding a 2 in front of H₂O: CH₄ + O₂ → CO₂ + 2H₂O
    • Step 3: Balance O by adding a 2 in front of O₂: CH₄ + 2O₂ → CO₂ + 2H₂O

    Balanced Equation: CH₄ + 2O₂ → CO₂ + 2H₂O

11. Al + O₂ → Al₂O₃
    • Step 1: Balance Al by adding a 4 in front of Al: 4Al + O₂ → 2Al₂O₃
    • Step 2: Balance O by adding a 3 in front of O₂: 4Al + 3O₂ → 2Al₂O₃

    Balanced Equation: 4Al + 3O₂ → 2Al₂O₃

12. C₃H₈ + O₂ → CO₂ + H₂O
    • Step 1: Balance C by adding a 3 in front of CO₂: C₃H₈ + O₂ → 3CO₂ + H₂O
    • Step 2: Balance H by adding a 4 in front of H₂O: C₃H₈ + O₂ → 3CO₂ + 4H₂O
    • Step 3: Balance O by adding a 5 in front of O₂: C₃H₈ + 5O₂ → 3CO₂ + 4H₂O

    Balanced Equation: C₃H₈ + 5O₂ → 3CO₂ + 4H₂O

13. KClO₃ → KCl + O₂
    • Step 1: Balance K and Cl (already balanced).
    • Step 2: Balance O by adding a 3 in front of O₂: 2KClO₃ → 2KCl + 3O₂

    Balanced Equation: 2KClO₃ → 2KCl + 3O₂

14. Mg + HCl → MgCl₂ + H₂
    • Step 1: Balance Mg (already balanced).
    • Step 2: Balance Cl and H by adding a 2 in front of HCl: Mg + 2HCl → MgCl₂ + H₂

    Balanced Equation: Mg + 2HCl → MgCl₂ + H₂

15. Ca(OH)₂ + HCl → CaCl₂ + H₂O
    • Step 1: Balance Ca (already balanced).
    • Step 2: Balance Cl and H by adding a 2 in front of HCl: Ca(OH)₂ + 2HCl → CaCl₂ + 2H₂O

    Balanced Equation: Ca(OH)₂ + 2HCl → CaCl₂ + 2H₂O

10. Na + H₂O → NaOH + H₂
    • Step 1: Balance Na (already balanced).
    • Step 2: Balance H by adding a 2 in front of NaOH and H₂O: 2Na + 2H₂O → 2NaOH + H₂

    Balanced Equation: 2Na + 2H₂O → 2NaOH + H₂

Balancing Chemical Equations Worksheet​ FAQs

What is a chemical equation?

A chemical equation is a symbolic representation of a chemical reaction. It shows the reactants (starting substances) on the left and the products (new substances formed) on the right, separated by an arrow. Example: H₂ + O₂ → H₂O

Why is it important to balance a chemical equation?

Balancing ensures that the Law of Conservation of Mass is followed. This law states that matter cannot be created or destroyed in a chemical reaction, so the number of atoms of each element must be the same on both sides of the equation.

What are coefficients in a chemical equation?

Coefficients are the numbers placed in front of chemical formulas to balance the equation. They indicate how many molecules or moles of a substance are involved in the reaction.

What is the difference between subscripts and coefficients?

Subscripts are part of the chemical formula and indicate the number of atoms in a molecule (e.g., H₂O means 2 hydrogen and 1 oxygen atom). Coefficients are added to balance the equation and affect the entire molecule (e.g., 2H₂O means 2 molecules of water).

How do I balance a chemical equation?

Follow these steps: 1. Write the unbalanced equation. 2. Count the number of atoms of each element on both sides. 3. Add coefficients to balance one element at a time. 4. Repeat until all elements are balanced. 5. Double-check your work.

What should I balance first in an equation?

Start with elements that appear in only one reactant and one product. Save hydrogen (H) and oxygen (O) for last since they often appear in multiple compounds.

What if I see a fraction in the coefficients?

If you get a fraction while balancing, multiply the entire equation by the denominator of the fraction to eliminate it. Example: N₂ + 3/2O₂ → 2NO. Multiply by 2: 2N₂ + 3O₂ → 4NO.

Can I change the subscripts to balance the equation?

No, you cannot change the subscripts. Changing subscripts changes the identity of the substance. Only coefficients can be changed to balance an equation.

What are some common mistakes to avoid while balancing equations?

Common mistakes include: Forgetting to count all atoms for each element, changing subscripts instead of coefficients, not double-checking the balanced equation, and ignoring polyatomic ions that remain unchanged.

What are the steps to solve a complex equation?

For complex equations: 1. Start with the most complicated molecule. 2. Balance elements that appear in one reactant and one product. 3. Leave single elements for last. 4. Check the total atom count for each element.

What if I can’t balance the equation?

If you’re stuck: 1. Break the equation into smaller parts. 2. Double-check your atom counts. 3. Start over and balance elements in a different order. 4. Practice simpler equations first.

Are there any tools to help balance equations?

Yes! Online equation balancers, practice worksheets, and visual aids like molecular diagrams are helpful tools to balance equations effectively.

How can I check if my equation is balanced?

Count the number of atoms for each element on both sides of the equation. If the counts match for every element, the equation is balanced.

What are polyatomic ions, and how do I balance them?

Polyatomic ions are groups of atoms that behave as a single unit (e.g., SO₄²⁻, NO₃⁻). If they remain unchanged during the reaction, balance them as a whole instead of balancing each atom individually.

Why is balancing chemical equations important in real life?

Balancing equations is essential for accurate measurements in reactions, crucial for medicine, engineering, and environmental science.