Chemistry and Chemical Reactivity (9th Edition)

Published by Cengage Learning
ISBN 10: 1133949649
ISBN 13: 978-1-13394-964-0

Chapter 17 Principles of Chemical Reactivity: Other Aspects of Aqueous Equilibria - Study Questions - Page 677a: 29

Answer

a) Equivalence: $0.0105\ M\times 36.78\ mL = c_{NH_3}\times 25.0\ mL$ $c=0.0154\ M$ b) Formed ammonium: $(0.0105\ M\times 36.78\ mL)/(25+36.78)=0.00625\ M$ Equilibrium: $K_a=x\cdot x/(0.00625-x)$ $x=1.87\cdot10^{-6}\ M=[H_3O^+],\ [NH_4^+]=0.00624\ M$ $[OH^-]=5.35\cdot10^{-9}\ M$ c) $pH=5.73$

Work Step by Step

a) Equivalence: $0.0105\ M\times 36.78\ mL = c_{NH_3}\times 25.0\ mL$ $c=0.0154\ M$ b) Formed ammonium: $(0.0105\ M\times 36.78\ mL)/(25+36.78)=0.00625\ M$ Equilibrium: $K_a=x\cdot x/(0.00625-x)$ $x=1.87\cdot10^{-6}\ M=[H_3O^+],\ [NH_4^+]=0.00624\ M$ $[OH^-]=5.35\cdot10^{-9}\ M$ c) $pH=5.73$
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