Ch.8 - Monoprotic Acid-Base EquilibriaWorksheetSee all chapters
All Chapters
Ch.1 - Chemical Measurements
Ch.2 - Tools of the Trade
Ch.3 - Experimental Error
Ch.4 + 5 - Statistics, Quality Assurance and Calibration Methods
Ch.6 - Chemical Equilibrium
Ch.7 - Activity and the Systematic Treatment of Equilibrium
Ch.8 - Monoprotic Acid-Base Equilibria
Ch.9 - Polyprotic Acid-Base Equilibria
Ch.10 - Acid-Base Titrations
Ch.11 - EDTA Titrations
Ch.12 - Advanced Topics in Equilibrium
Ch.13 - Fundamentals of Electrochemistry
Ch.14 - Electrodes and Potentiometry
Ch.15 - Redox Titrations
Ch.16 - Electroanalytical Techniques
Ch.17 - Fundamentals of Spectrophotometry
BONUS: Chemical Kinetics
Arrhenius Acids and Bases
Bronsted-Lowry Acids and Bases
Lewis Acids and Bases
Ka and Kb of compounds
Weak Acid-Base Equilibria
Ionic Salts of Weak Acids and Bases

WEAK ACIDS and WEAK BASES are weak electrolytes that do not completely ionize in solution, but instead form an equilibrium. 

Weak Acid-Base Equilibria

Example #1: What is the original molarity of a solution of weak acid with a Ka of 4.7 x 10-3 and pH of 4.12 at 25 oC?

Example #2: You are seeking to identify an unknown monoprotic acid by determining its Ka value. A 6.05 x 10-2 M solution of this unknown monoprotic acid has a pH of 2.122. Determine the Ka of this unknown acid?

a) 4.47 x 10-4
b) 9.42 x 10-4
c) 2.85 x 10-2
d) 1.08 x 10-3
e) 3.58 x 10-1

Example #3: A weak acid has a pKa of 5.35. What is the hydronium ion concentration in a 0.10 M solution of this weak acid?

a) 5.4 x 10-4 M

b) 6.3 x 10-6 M

c) 3.5 x 10-5 M

d) 2.3 x 10-6 M

e) 4.5 x 10-6 M

f) 6.7 x 10-4 M

Practice: The pH of an aqueous 0.10 M nitrite ion is 8.17. What is the base dissociation constant of the base?