---
title: "A student uses the particulate model shown below to represent the individual steps of bond cleavage and bond formation during the gas-phase synthesis of ammonia.  \\[ \\text{N}_2(g) + 3\\text{ H}_2(g) \\rightarrow 2\\text{ NH}_3(g) \\]  Stage 1 represents the initial reactant mixture, Stage 2 represents the transition to isolated gaseous atoms, and Stage 3 represents the product mixture. Which of the following best describes the energy changes associated with the transitions from Stage 1 to Stage 2 and from Stage 2 to Stage 3?"
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url: "https://nerd-notes.com/ubq/123807/"
date_modified: "2026-09-28T12:30:23+00:00"
---

# A student uses the particulate model shown below to represent the individual steps of bond cleavage and bond formation during the gas-phase synthesis of ammonia.

\[ \text{N}_2(g) + 3\text{ H}_2(g) \rightarrow 2\text{ NH}_3(g) \]

Stage 1 represents the initial reactant mixture, Stage 2 represents the transition to isolated gaseous atoms, and Stage 3 represents the product mixture. Which of the following best describes the energy changes associated with the transitions from Stage 1 to Stage 2 and from Stage 2 to Stage 3?

A student uses the particulate model shown below to represent the individual steps of bond cleavage and bond formation during the gas-phase synthesis of ammonia.

\[ \text{N}_2(g) + 3\text{ H}_2(g) \rightarrow 2\text{ NH}_3(g) \]

Stage 1 represents the initial reactant mixture, Stage 2 represents the transition to isolated gaseous atoms, and Stage 3 represents the product mixture. Which of the following best describes the energy changes associated with the transitions from Stage 1 to Stage 2 and from Stage 2 to Stage 3?

![A grayscale diagram with three side-by-side rectangular boxes labeled Stage 1, Stage 2, and Stage 3 from left to right, with horizontal rightward arrows connecting Stage 1 to Stage 2 and Stage 2 to Stage 3. A legend at the top maps: large solid black sphere = N atom; small open white sphere = H atom. The Stage 1 box contains exactly one diatomic molecule consisting of two touching large solid black spheres and three separate diatomic molecules each consisting of two touching small open white spheres. The Stage 2 box contains exactly two unbonded large solid black spheres and exactly six unbonded small open white spheres distributed evenly without touching. The Stage 3 box contains exactly two separate ammonia molecules, each consisting of one central large solid black sphere touching three small open white spheres in a trigonal arrangement. No other particles, labels, text, or annotations appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1790598622-VB2FHQ.jpg)

- **A.** Energy is released from Stage 1 to Stage 2 because chemical bonds are broken, and energy is absorbed from Stage 2 to Stage 3 because chemical bonds are formed.
- **B.** Energy is released from Stage 1 to Stage 2 because potential energy increases, and energy is absorbed from Stage 2 to Stage 3 because potential energy decreases.
- **C.** Energy is absorbed from Stage 1 to Stage 2 because covalent bonds are broken, and energy is released from Stage 2 to Stage 3 because new covalent bonds are formed.
- **D.** Energy is absorbed from Stage 1 to Stage 2 because intermolecular forces are overcome, and energy is released from Stage 2 to Stage 3 because new intermolecular forces are established.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/123807/*