1. Combustion of Methane
Unbalanced:​
CH₄ + O₂ → CO₂ + H₂O
Balanced:​
CH₄ + 2O₂ → CO₂ + 2H₂O
Explanation:​
In this combustion reaction, methane (CH₄) reacts with oxygen (O₂) to produce carbon dioxide
(CO₂) and water (H₂O). By balancing the atoms on both sides, we ensure that we have the same
number of atoms of each element on each side of the equation.
2. Formation of Water from Hydrogen and Oxygen
Unbalanced:​
H₂ + O₂ → H₂O
Balanced:​
2H₂ + O₂ → 2H₂O
Explanation:​
We need 2 molecules of hydrogen gas (H₂) to react with 1 molecule of oxygen gas (O₂) to
produce 2 molecules of water (H₂O).
3. Reaction between Sodium and Chlorine to form Sodium Chloride
Unbalanced:​
Na + Cl₂ → NaCl
Balanced:​
2Na + Cl₂ → 2NaCl
Explanation:​
To balance this, we need 2 sodium atoms (Na) for every chlorine molecule (Cl₂), resulting in 2
molecules of sodium chloride (NaCl).
4. Decomposition of Calcium Carbonate
Unbalanced:​
CaCO₃ → CaO + CO₂
Balanced:​
CaCO₃ → CaO + CO₂
Explanation:​
This equation is already balanced. One molecule of calcium carbonate (CaCO₃) decomposes
into one molecule of calcium oxide (CaO) and one molecule of carbon dioxide (CO₂).
5. Reaction between Aluminum and Oxygen to form Aluminum Oxide
Unbalanced:​
Al + O₂ → Al₂O₃
Balanced:​
4Al + 3O₂ → 2Al₂O₃
Explanation:​
To balance this, we need 4 aluminum atoms (Al) and 3 oxygen molecules (O₂) to form 2
molecules of aluminum oxide (Al₂O₃).