Problem 97 - Chemistry An Atoms First Approach

Question

A common demonstration in chemistry courses involves adding a tiny speck of manganese(IV) oxide to a concentrated hydrogen peroxide \(\left(\mathrm{H}_{2} \mathrm{O}_{2}\right)\) solution. Hydrogen peroxide decomposes quite spectacularly under these conditions to produce oxygen gas and steam (water vapor). Manganese(IV) oxide is a catalyst for the decomposition of hydrogen peroxide and is not consumed in the reaction. Write the balanced equation for the decomposition reaction of hydrogen peroxide.

Step-by-Step Solution

Answer

The balanced equation for the decomposition reaction of hydrogen peroxide, catalyzed by manganese(IV) oxide, is: \( 2 \mathrm{H}_{2} \mathrm{O}_{2} \rightarrow \mathrm{O}_{2} + 2 \mathrm{H}_{2} \mathrm{O} \)

Step 1: Write the unbalanced equation

To begin, let's write down the unbalanced equation for the reaction, with reactants on the left and products on the right: H₂O₂ → O₂ + H₂O This equation represents the decomposition of hydrogen peroxide into oxygen gas and water.

Step 2: Checking for catalyst

Since manganese(IV) oxide is a catalyst, it does not take part in the reaction, and thus it will not be included in the balanced chemical equation.

Step 3: Balancing the equation

Now, let's balance the chemical equation. We'll start by counting the atoms of each element on the reactant and product sides: Reactants: 2 H atoms 2 O atoms Products: 2 H atoms 2 + 1 = 3 O atoms The hydrogen atoms are already balanced, but there is one extra oxygen atom in the products. To balance the equation, we can add coefficients before the chemical species to equalize the number of atoms for each element: 2 H₂O₂ → O₂ + 2 H₂O Now, we have: Reactants: 4 H atoms 4 O atoms Products: 4 H atoms 2 + 2 = 4 O atoms The equation is now balanced.

Step 4: Write the balanced equation

The balanced equation for the decomposition reaction of hydrogen peroxide is: 2 H₂O₂ → O₂ + 2 H₂O