http://www.ck12.org Chapter 19. Chemical Equilibrium
CHAPTER
(^19) Chemical Equilibrium
Chapter Outline
19.1 The Nature of Chemical Equilibrium
19.2 APPLICATIONS OFEQUILIBRIUMCONSTANTS
19.3 FACTORSAFFECTINGCHEMICALEQUILIBRIA
19.4 REFERENCES
When dissolved in water, cobalt chloride produces a reddish-pink solution. The introduction of additional chloride
ions causes a shift from a fully hydrated cobalt cation ([Co(H 2 O) 6 ]^2 +(aq)) to a new complex ([CoCl 4 ]2 ̆(aq)). This
is accompanied by a change in color, from reddish-pink to blue. The green solution shown in the figure above is a
third type of cobalt complex. The equilibrium between the two complexes is sensitive not only to the concentration
of the chloride ion, but also to the temperature. Increasing the temperature causes a shift from the pink to the blue
species, and lowering the temperature reverses this color change.
So far, we have generally assumed that the reactants in a chemical reaction are irreversibly transformed into products.
However, many chemical reactions are reversible, meaning that it is also possible for the reaction to go "backwards".
When both the forward and reverse reactions can proceed at a reasonable rate, a state of equilibrium is eventually
reached, in which both reactions are occurring at the same rate and no net change is made to the amounts of reactants
or products. In this chapter, we will look at the factors that govern chemical equilibria.
U ser:Chemicalinterest/Wikimedia Commons.commons.wikimedia.org/wiki/File:Cobalt_chloride_equilibrium.JPG.Public Domain.