Question

Hydrogen peroxide can be used to disinfect and clean surfaces around the home. It breaks down over time into oxygen gas and water.
Consider the following reaction:
Some amount of hydrogen peroxide (H2O2) reacts to produce 1 molecule of oxygen (O2) and 2 molecules of water (H2O).
Use the number of atoms in the reaction to answer the question below.
Chemical element Number of atoms in the reaction
H 4
O 4
During this reaction, how many molecules of hydrogen peroxide (H2O2) react?

Answer 1

To determine how many molecules of hydrogen peroxide (H₂O₂) react, we can start by writing the balanced chemical equation for the decomposition of hydrogen peroxide:

\[ 2 \text{H}_2\text{O}_2 \rightarrow \text{O}_2 + 2 \text{H}_2\text{O} \]

From the equation, we can see that:

- 2 molecules of hydrogen peroxide (H₂O₂) produce 1 molecule of oxygen (O₂) and 2 molecules of water (H₂O).

Now, let's analyze the atom count:
- Each molecule of H₂O₂ contains 2 hydrogen atoms and 2 oxygen atoms.
- Therefore, 2 molecules of H₂O₂ will contain:
- \( 2 \times 2 = 4 \) hydrogen atoms
- \( 2 \times 2 = 4 \) oxygen atoms

This matches the total provided in your question, where you have 4 hydrogen atoms and 4 oxygen atoms.

Thus, the answer is that **2 molecules of hydrogen peroxide (H₂O₂)** react to produce 1 molecule of oxygen and 2 molecules of water.