ADDITIONAL ASPECTS OF AQUEOUS EQUILIBRIA

the most common and most important solvent on Earth, occupies its position of importance because of its abundance and its exceptional ability to dissolve a wide variety of substances. Coral reefs are a striking example of aqueous chemistry at work in nature. Coral reefs are built by tiny animals called stony corals, which secrete a hard calcium carbonate exoskeleton. 

Over time, the stony corals build up large networks of calcium carbonate upon which a reef is built. The size of such structures can be immense, as illustrated by the Great Barrier Reef. 

Stony corals make their exoskeletons from dissolved Ca and ions. This pro- 

This lowers the pH of the ocean and leads to a decreaise in the C03 concentration. As a result it becomes more difficult for stony corals and other importemt oceem creatures to maintain their exoskeletons. We will take a closer look at the consequences of oceem acidification later in the chapter. 

To understand the chemistry that underlies coral reef formation and other processes in the ocean and in aqueous systems such as living cells, we must understand the concepts of aqueous equilibria. In this chapter, we teike a step towcud understanding such complex solutions by looking first at further apphcations of acid-base equilibria. The idea is to consider not only solutions in which there is a single solute but 

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