AP Chemistry Unit 9.1: Entropy

White phosphorus is composed of $\mathrm{P}_{4}$ molecules with a tetrahedral structure, as shown in the

diagram on the left. Each P atom is bonded to the other three P atoms by single bonds, as shown

in the incomplete Lewis diagram on the right.

The reaction of white phosphorus with oxygen to form $\mathrm{P}_{4} \mathrm{O}_{10}(s)$ is thermodynamically

favorable at 298 K. The reaction is represented by equation 1.

The entropy change of the reaction, $\Delta S^{\circ}$, is negative. Using particle-level reasoning,

explain why the entropy decreases as the reaction progresses.