---
title: "A rigid, sealed \\(1.0 \\text{ L}\\) reaction vessel is charged with non-zero initial concentrations of three gaseous species, \\(\\text{X(g)}\\), \\(\\text{Y(g)}\\), and \\(\\text{Z(g)}\\), at a constant temperature. The graph below shows the concentration of each gas as a function of time until dynamic equilibrium is established at time \\(t_{\\text{eq}}\\).  Based on the data in the graph, which of the following gives the correct balanced chemical equation for the reaction and the value of the equilibrium constant, \\(K_c\\), at this temperature?"
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url: "https://nerd-notes.com/ubq/123863/"
date_modified: "2026-09-28T12:30:36+00:00"
---

# A rigid, sealed \(1.0 \text{ L}\) reaction vessel is charged with non-zero initial concentrations of three gaseous species, \(\text{X(g)}\), \(\text{Y(g)}\), and \(\text{Z(g)}\), at a constant temperature. The graph below shows the concentration of each gas as a function of time until dynamic equilibrium is established at time \(t_{\text{eq}}\).

Based on the data in the graph, which of the following gives the correct balanced chemical equation for the reaction and the value of the equilibrium constant, \(K_c\), at this temperature?

A rigid, sealed \(1.0 \text{ L}\) reaction vessel is charged with non-zero initial concentrations of three gaseous species, \(\text{X(g)}\), \(\text{Y(g)}\), and \(\text{Z(g)}\), at a constant temperature. The graph below shows the concentration of each gas as a function of time until dynamic equilibrium is established at time \(t_{\text{eq}}\).

Based on the data in the graph, which of the following gives the correct balanced chemical equation for the reaction and the value of the equilibrium constant, \(K_c\), at this temperature?

![A grayscale line graph plotting concentration versus time in a closed container at constant temperature. The vertical axis is labeled 'Concentration (M)' with tick marks at 0.00, 0.20, 0.40, 0.60, and 0.80. The horizontal axis is labeled 'Time (min)' with ticks at 0 and at a point labeled t_eq. Three distinct curves are plotted from time 0 to past t_eq without gridlines: 1. A solid black curve labeled 'X' starts at (0, 0.70), curves smoothly downward, and plateaus horizontally at exactly 0.30 M at t_eq. 2. A dashed black curve labeled 'Y' starts at (0, 0.40), curves smoothly downward, and plateaus horizontally at exactly 0.20 M at t_eq. 3. A dotted black curve labeled 'Z' starts at (0, 0.20), curves smoothly upward, and plateaus horizontally at exactly 0.60 M at t_eq. All three curves remain completely flat and horizontal to the right of t_eq. No other lines, curves, gridlines, text, or annotations appear.](https://nerd-notes.com/wp-content/uploads/ubq-frq-generated/stem-fig-1-1790598636-Oi0ZpU.jpg)

- **A.** The balanced equation is \(\text{X(g)} + 2\,\text{Y(g)} \rightleftharpoons 2\,\text{Z(g)}\), and \(K_c = 30\).
- **B.** The balanced equation is \(2\,\text{X(g)} + \text{Y(g)} \rightleftharpoons 2\,\text{Z(g)}\), and \(K_c = 6.0\).
- **C.** The balanced equation is \(2\,\text{X(g)} + \text{Y(g)} \rightleftharpoons 2\,\text{Z(g)}\), and \(K_c = 10\).
- **D.** The balanced equation is \(2\,\text{X(g)} + \text{Y(g)} \rightleftharpoons 2\,\text{Z(g)}\), and \(K_c = 20\).

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/123863/*