Question

Balance the following chemical equations: \(H_2 + O_2 \rightarrow H_2O\) and \(NaOH + HCl \rightarrow NaCl + H_2O\).

Hint:

Always balance the chemical equation by ensuring that the number of atoms of each element is the same on both sides of the equation.

Answer 1

Concept: According to the law of conservation of mass, the number of atoms of each element must be the same on both sides of a chemical equation. Therefore, chemical equations must be balanced.
Step 1:Balancing the equation \(H_2 + O_2 \rightarrow H_2O\) Unbalanced equation: \[ H_2 + O_2 \rightarrow H_2O \] Number of oxygen atoms on the left side is 2, while on the right side it is 1. To balance oxygen atoms, multiply \(H_2O\) by 2. \[ H_2 + O_2 \rightarrow 2H_2O \] Now hydrogen atoms become 4 on the right side, so multiply \(H_2\) by 2. \[ 2H_2 + O_2 \rightarrow 2H_2O \] This is the balanced equation.
Step 2:Balancing the equation \(NaOH + HCl \rightarrow NaCl + H_2O\) Unbalanced equation: \[ NaOH + HCl \rightarrow NaCl + H_2O \] Counting atoms on both sides:

• Na: 1 on both sides
• Cl: 1 on both sides
• H: 2 on both sides
• O: 1 on both sides

Since all atoms are already equal, the equation is already balanced. \[ NaOH + HCl \rightarrow NaCl + H_2O \]