Which of the following particle diagrams best represents the products when four molecules of H2O2(l) — Stoichiometry Chemistry Question

STEPS:

1. Write and balance the chemical equation for the decomposition reaction:
Hydrogen peroxide decomposes into liquid water and oxygen gas according to the following balanced equation:
$$2\ \text{H}_2\text{O}_2(l) \rightarrow 2\ \text{H}_2\text{O}(l) + \text{O}_2(g)$$

2. Apply the stoichiometry of the reaction to the given quantity of reactants:
The balanced equation shows a $2:2:1$ stoichiometric ratio between the reactant ($\text{H}_2\text{O}_2$) and the products ($\text{H}_2\text{O}$ and $\text{O}_2$). Therefore, if 4 molecules of $\text{H}_2\text{O}_2$ undergo complete decomposition, they must yield:
* Water molecules produced: $4\ \text{molecules H}_2\text{O}_2 \times \frac{2\ \text{H}_2\text{O}}{2\ \text{H}_2\text{O}_2} = \mathbf{4\ \text{molecules of H}_2\text{O}}$
* Oxygen gas molecules produced: $4\ \text{molecules H}_2\text{O}_2 \times \frac{1\ \text{O}_2}{2\ \text{H}_2\text{O}_2} = \mathbf{2\ \text{molecules of O}_2}$

3. Verify the conservation of mass (atom count):
* Reactants side: 4 molecules of $\text{H}_2\text{O}_2$ contain a total of 8 hydrogen atoms (represented as dark gray spheres) and 8 oxygen atoms (represented as large white spheres).
* Products side:
* 4 molecules of water ($\text{H}_2\text{O}$) account for 8 hydrogen atoms and 4 oxygen atoms.
* 2 molecules of diatomic oxygen ($\text{O}_2$) account for the remaining 4 oxygen atoms.
* The total atom counts match exactly, confirming that mass is conserved.

4. Identify the matching particle diagram:
The correct diagram must display exactly 4 water molecules (each depicted as 1 white sphere bonded to 2 dark gray spheres) and 2 oxygen gas molecules (each depicted as 2 white spheres bonded together). This corresponds to Option D.

*

WHY_OTHERS_WRONG:

• Option A is incorrect: This diagram represents a complete dissociation of the substances into four single hydrogen atoms and four single oxygen atoms. It does not represent the correct molecular products ($\text{H}_2\text{O}$ and $\text{O}_2$) and fails to conserve the total number of atoms originally present.
• Option B is incorrect: This diagram depicts isolated, unbonded atoms of hydrogen and oxygen. Chemical reactions produce stable, covalently bonded compounds; oxygen and water do not exist as monoatomic species at room temperature.
• Option C is incorrect: This diagram correctly shows 4 water molecules but represents the other product as 2 hydrogen gas molecules ($\text{H}_2$) (depicted as pairs of bonded dark gray spheres) instead of oxygen gas molecules ($\text{O}_2$). This violates both the chemical identity of the products and the stoichiometry of the reaction.