Balancing Chemical Equations

Key Concepts

• Balanced Equation: An equation is balanced when there is an equal number of atoms of each element on both sides.
• Balancing Method: Only change the coefficients (numbers in front) of formulas, not the formulas themselves.
• State Symbols:
  • (s) = solid
  • (l) = liquid
  • (g) = gas
  • (aq) = aqueous (dissolved in water)

Steps to Balance an Equation

1. Count Atoms: Identify how many atoms of each element are present on both sides of the equation.
2. Compare: Determine if the numbers are equal. If so, the equation is balanced.
3. Adjust Coefficients: If not balanced, adjust the coefficients in front of formulas to equalize the number of atoms of each element.
   • Start with elements that appear only once on each side.
4. Iterate: Repeat the process until the equation is balanced.

Example:

• Given: ( \text{CH}_4 + \text{O}_2 \rightarrow \text{CO}_2 + \text{H}_2\text{O} )
  • Balance the number of C, H, and O atoms.

Practice Questions

1. Balance: ( \text{Ca} + \text{O}_2 \rightarrow \text{CaO} )
2. Balance: ( \text{Na}_2\text{O} + \text{H}_2\text{O} \rightarrow \text{NaOH} )
3. Balance: ( \text{Al} + \text{O}_2 \rightarrow \text{Al}_2\text{O}_3 )
4. Balance: ( \text{Na} + \text{Cl}_2 \rightarrow \text{NaCl} )
5. Balance: ( \text{Na}_2\text{CO}_3 \rightarrow \text{Na}_2\text{O} + \text{CO}_2 )
6. Balance: ( \text{K} + \text{O}_2 \rightarrow \text{K}_2\text{O} )
7. Balance: ( \text{C}_4\text{H}_8 + \text{O}_2 \rightarrow \text{CO}_2 + \text{H}_2\text{O} )
8. Balance: ( \text{Fe}_2\text{O}_3 + \text{HCl} \rightarrow \text{FeCl}_3 + \text{H}_2\text{O} )
9. Balance: ( \text{F}_2 + \text{KBr} \rightarrow \text{KF} + \text{Br}_2 )
10. Balance: ( \text{C}5\text{H}{12} + \text{O}_2 \rightarrow \text{CO}_2 + \text{H}_2\text{O} )
11. Balance: ( \text{NH}_3 + \text{O}_2 \rightarrow \text{NO} + \text{H}_2\text{O} )
12. Balance: ( \text{HNO}_3 \rightarrow \text{NO}_2 + \text{H}_2\text{O} + \text{O}_2 )

Use these examples and the method described to practice balancing chemical equations. Review each equation, compare the atoms on each side, and adjust coefficients as necessary to achieve balance.