Chapter 16 Text
Chapter 16 Text
Chapter 16 Text
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<strong>16</strong>.7 Weak Bases 637<br />
equilibrium reactions, and values of Kb for several weak bases in water. Appendix<br />
D includes a more extensive list. These bases contain one or more lone pairs of<br />
electrons because a lone pair is necessary to form the bond with H+. Notice that<br />
in the neutral molecules in Table <strong>16</strong>.4 the ]one pairs are on nitrogen atoms. The<br />
other bases listed are anions derived from weak acids.<br />
SAMPLE EXERCISE <strong>16</strong>.14<br />
Calculate the concentration of OH" in a 0.15 M solution of NH3.<br />
Solution<br />
Analyze: We are given the concentration of a weak base and are asked to determine<br />
the concentration of OH~.<br />
Plan: We will use essentially the same procedure here as used in solving problems<br />
involving the ionization of weak acids, that is, we write the chemical equation and<br />
tabulate initial and equilibrium concentrations.<br />
Solve: We first write the ionization reaction and the corresponding equilibrium-constant<br />
(K(,) expression.<br />
NH3(fl