Write the balanced reduction half-reaction for the decomposition of hydrogen peroxide.
To find the balanced reduction half-reaction for the decomposition of hydrogen peroxide (H2O2), we need to first determine the products formed and then balance the equation.
The decomposition of hydrogen peroxide can proceed in two ways:
1. Formation of water: H2O2 -> H2O + O2
2. Formation of water and oxygen: H2O2 -> H2O + 1/2 O2
Let's consider the second reaction, which is the most commonly observed. Here is how you can balance the reduction half-reaction:
Step 1: Write the unbalanced reduction half-reaction:
H2O2 -> H2O
Step 2: Balance the atoms other than oxygen and hydrogen. In this case, we only need to balance the oxygen atoms.
Since there is one oxygen atom on the left side and two on the right side, we need to add a coefficient of 2 in front of H2O.
H2O2 -> 2H2O
Step 3: Balance the hydrogen atoms by adding the appropriate number of protons (H⁺) to the left side of the equation.
H2O2 + 2H⁺ -> 2H2O
Step 4: Balance the charge by adding electrons (e⁻) to one side of the equation.
H2O2 + 2H⁺ + 2e⁻ -> 2H2O
Finally, the balanced reduction half-reaction for the decomposition of hydrogen peroxide is:
H2O2 + 2H⁺ + 2e⁻ -> 2H2O