Graphs and Le Chatelier's Principle

Graphs and Le Chatelier's principle

Graphs can be used to represent data about equilibrium reactions. The following are some points to keep in mind when presented with a graph.

1. Identify the type of graph by looking at the label on the y-axis. You will find either:

   1. a rate-time graph

   2. a mole-time or concentration-time graph

2. For rate-time graphs, when the rate for the forward reaction and the rate for the reverse reaction are equal, the system is in equilibrium.

   

3. For concentration-time graphs or mole-time graphs equilibrium occurs where the concentration or number of moles of the reactants and products are constant. These values need not be equal to one another.

   

4. When calculating \(\text{K}_{\text{c}}\) make sure you only take values from the sections of the graph where the y-value is constant. \(\text{K}_{\text{c}}\) can only be calculated when the system is in equilibrium.