Cave explorers are very familiar with stalactites and stalagmites. These picturesque formations occur as water rich in minerals seeps through the ground and drips from the ceiling of the cave. One of the prominent minerals in the water is calcium carbonate, an ionic compound that is nearly insoluble in water. As the water evaporates, precipitates of calcium carbonate, colored by the presence of other ions, form and harden. Stalactites are the icicle-like structures that hang from the ceiling, while stalagmites grow upward from the ground. When they meet, spectacular columns form, as seen above. The solubility of ionic compounds involves an equilibrium that occurs between the solid compound and the ions in a solution. However, equilibrium is a general concept that applies to more than just precipitation reactions. In this chapter, you will learn about different types of equilibrium and how changes to the reaction conditions can manipulate that equilibrium, thus increasing or decreasing the amount of products formed in a reaction.
Opening image copyright Jason Patrick Ross, 2012. www.shutterstock.com. Used under license from Shutterstock.com.