Ch.15 - Acid and Base EquilibriumWorksheetSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds
Problem

Codeine (Cod), a drug used in pain killers and cough medicine, is a naturally occurring amine that has a Kb = 1.6 ×10–6. What is the pH of a 0.0012 M solution of codeine?

A. 8.45 

B. 4.80 

C. 10.25 

D. 9.64 

E. 4.36

Solution

We are being asked to calculate the pH for a 0.0012 M solution of codeine (Cod)


Codeine (Cod) has a low Kb, therefore we know that it is a weak base.


Since we’re dealing with a weak base and Kb is an equilibrium expression, we will have to create an ICE chart to determine the equilibrium concentration of each species:

Codweak baseproton acceptor
H2O → will act as the weak acidproton donor


Equilibrium reaction:        Cod(aq) + H2O(l)  CodH+(aq) + OH-(aq)

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