Ch.15 - Acid and Base EquilibriumWorksheetSee all chapters
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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

Solution: For a weak diprotic acid H2X, what is the relationship between [X2-] and Ka2? Under what conditions does this relationship exist?

Solution: For a weak diprotic acid H2X, what is the relationship between [X2-] and Ka2? Under what conditions does this relationship exist?

Problem

For a weak diprotic acid H2X, what is the relationship between [X2-] and Ka2? Under what conditions does this relationship exist?

Solution

We want to know the relationship between the anion [X2-] and Ka2 that is formed by a diprotic acid.


Diprotic acids, such as sulfuric acid (H2SO4), carbonic acid (H2CO3), hydrogen sulfide (H2S), chromic acid (H2CrO4), and oxalic acid (H2C2O4) have two acidic hydrogen atoms. These two acidic hydrogen atoms dissociate stepwise so there are two Kexpressions.


Consider the ionization of a general diprotic acid H2X.

The general Ka expression for acids is:


Ka=productsreactants


H2X(aq) + H2O(l) → H3O+(aq) + HX-(aq)

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