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.

Short answer

The balanced equation for the decomposition of hydrogen peroxide (\(\mathrm{H}_{2}\mathrm{O}_{2}\)) is: \[ 2\, \mathrm{H}_{2}\mathrm{O}_{2} \rightarrow \mathrm{O}_{2} + 2\, \mathrm{H}_{2}\mathrm{O} \]

Step-by-step solution

Write the unbalanced chemical equation for the decomposition of hydrogen peroxide.

The decomposition reaction of hydrogen peroxide (\(\mathrm{H}_{2}\mathrm{O}_{2}\)) produces oxygen gas (O\(_{2}\)) and water vapor (H\(_{2}\)O): \[ \mathrm{H}_{2}\mathrm{O}_{2} \rightarrow \mathrm{O}_{2} + \mathrm{H}_{2}\mathrm{O} \]

Balance the chemical equation.

To balance the equation, we need to account for all of the atoms on both sides of the equation. Currently, there are 2 hydrogen atoms and 2 oxygen atoms on the left side of the equation and 3 oxygen atoms and 2 hydrogen atoms on the right side. To balance the equation, we will need two molecules of hydrogen peroxide and two molecules of water on the right side: \[ 2\, \mathrm{H}_{2}\mathrm{O}_{2} \rightarrow \mathrm{O}_{2} + 2\, \mathrm{H}_{2}\mathrm{O} \] Now, there are a total of 4 hydrogen atoms and 4 oxygen atoms on both sides of the equation, so the equation is balanced.