Equilibrium Expressions - Kp, Ka, Kb, Ksp, and Keq

Sometimes, chemical reactions can contain both a forward process and a reverse process. At times, these processes are considered to be in equilibrium. For a moment, consider the dissolving process. If salt is added to water, a solution is created. Then, through the reversing process of evaporation, you are once again left with salt. Freezing and melting are also great examples of a forward and reverse reaction. Ice that is subjected to warmer temperatures will melt, becoming water. If the water is subjected to cold temperatures it will freeze again.

You may think: how are these reactions in equilibrium, since water is either frozen and solid, or melting and liquid? The reactions are not in static equilibrium; instead, they are in dynamic equilibrium. In a dynamic equilibrium for a reversible chemical reaction, the forward and reverse reactions rates are equal. This allows for the reactants and products to constantly change back and forth without a change in the amount of either. Because the reactions are in dynamic equilibrium, the concentrations of the reactions and products are unchanged. There is also no change to the rates of the reactions.

If a reaction is reversible, multi-directional reaction arrows are used to notate if forward or reverse reactions are favored. Before you learn about forward and reverse notation, how to write a equilibrium expression, and how to calculate the equilibrium constants, you will need to analyze each reaction to see if it reversible. In this non-graded activity, read the description of each reaction. Then, select whether the reaction is reversible or irreversible and click SUBMIT to check your responses. Click on the interactivity thumbnail, and then click NEXT to get started.

The Equilibrium Expression and Constant

Learn how chemists setup an equilibrium expression and then solve for the equilibrium constant. The equilibrium constant, K, expresses the relationship between products and reactants of a reaction. View this presentation to learn how to write an equilibrium expression and solve for the equilibrium constant.

View a printable version of the interactivity.

 

Equilibrium Expressions Review

Now that you have learned about equilibrium reactions, complete this non-graded activity to check your knowledge. Review each reaction and use your cursor to select the correct equilibrium expression. Then, click SUBMIT to check your responses. Click on the interactivity thumbnail, and click NEXT to get stated.