Key Principles of Balancing Equations
- Conservation of Mass: An equation is balanced when there are the same number of atoms of each type on both sides of the equation.
- Coefficient Rules: An equation can only be balanced by putting numbers in front of formulas – you cannot change the formula itself.
- State Symbols: (s) = solid, (l) = liquid, (g) = gas, (aq) = aqueous (dissolved in water)
How to Balance Chemical Equations
- Count the atoms of each element on both sides of the equation
- Check if the numbers match - if they do, the equation is balanced
- Add coefficients (numbers) in front of compounds to balance atoms
- Begin with elements that appear in only one compound on each side
- Continue adjusting until all atoms are equal on both sides
Example with Solution
Worked Example: Mg + O2 → MgO
Click to see solution
2Mg + O2 → 2MgO
Practice Questions
1) Zn + HCl → ZnCl2 + H2