When a diatomic gas X2\text{X}_2X2 is placed in a sealed flask, it dissociates to form a mononuclear gas X\text{X}X.
The equation for the reaction is
X2(g)⇌2X(g) \text{X}_2(\text{g}) \rightleftharpoons 2\text{X}(\text{g}) X2(g)⇌2X(g) red-brown gas⇌colourless gas \text{red-brown gas} \rightleftharpoons \text{colourless gas} red-brown gas⇌colourless gasA sample of pure X2\text{X}_2X2 is placed in a sealed flask at 300 K300\text{ K}300 K. The flask is left until a dynamic equilibrium is reached.
For a reaction that is in dynamic equilibrium, the forward and backward reactions occur at the same time.
State two other features of a reaction that is in dynamic equilibrium.
At equilibrium, there is more X2\text{X}_2X2 than X\text{X}X.
The graph shows how the amount of X2\text{X}_2X2 in the sealed flask changes with time.
If you were to draw a cross (×\times×) on the graph to show the point where the reaction first reaches equilibrium, describe where it should be placed.
Describe the start point, shape, and final level of the curve you would draw on the same graph to show how the amount of X\text{X}X in the sealed flask changes over the same time period.
The sealed flask containing the equilibrium mixture is placed in a beaker of ice-cold water. The mixture becomes a deeper red-brown in colour.
Explain what this observation shows about the forward reaction.
