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Chemistry LibreTexts

6: Equilibrium Chemistry

Regardless of the problem on which an analytical chemist is working, its solution requires a knowledge of chemistry and the ability to apply that knowledge. For example, an analytical chemist studying the effect of pollution on spruce trees needs to know, or know where to find, the chemical differences between p‑hydroxybenzoic acid and p‑hydroxyacetophenone, two common phenols found in the needles of spruce trees. Your ability to “think as a chemist” is a product of your experience in the classroom and in the laboratory. The material in this text assumes your familiarity with topics from earlier courses. Because of its importance to analytical chemistry, this chapter provides a review of equilibrium chemistry. Much of the material in this chapter should be familiar to you, although some topics—ladder diagrams and activity, for example—afford you with new ways to look at equilibrium chemistry.

Thumbnail: The \(N_2O_{(g)} \rightleftharpoons 2NO_{2(g)}\) system at Different Temperatures. Nitrogen dioxide (\(NO_2\)) gas converts to the colorless gas dinitrogen tetroxide (\(N_2O_4\)) at low temperatures, and converts back to \(NO_2\) at higher temperatures. The bottles in this photograph contain equal amounts of gas at different temperatures. Figure used with permission from Wikipedia (CC BY-SA 3.0).