Introduces protolysis as the transfer of a proton between acids and bases, then compares the Arrhenius, Brønsted-Lowry and Lewis theories, noting the limitations of each. It goes on to cover protolyte strength through Ka, Kb, pKa and pKb, including polyprotic acids and the pKa-pKb relationship, and lists intramolecular, external and solvent factors affecting strength with exceptions such as hydrogen halides. It ends with a formulas section covering the dissociation constants and the Henderson-Hasselbalch equation.
Topic 12 of 42 in the MU Sofia syllabus for Chemistry (Dental Medicine, Year 1). The free AceMed note covers it in 12 sections, about 963 words (8 min of reading), with 19 flashcards.
In this note
Protolysis Processes:
Acids and bases. Classical concept of acid and bases - Arrhenius theory.
Theory of Broensted - Lowry for acids and bases.
Lewis's theory of acids and bases
Strength of acids and bases. Acid and base ionization constants. рКаand рКb.
Factors Affecting Strength of Protolytes
High-Yield Formulas & Relations (Acids & Bases)
Acid Dissociation Constant (Ka)
Base Dissociation Constant (Kb)
pKa and pKb
Relationship Between pKa and pKb
Henderson–Hasselbalch Equation (Buffer Equation)
Protolysis Processes:
Definition:
Protolysis processes involve the transfer of a proton (H⁺) from an acid to a base.
This proton transfer is fundamental to understanding acid-base reactions.
Classification of Acids and Bases:
While the terms "acid" and "base" are commonly used, there are multiple theories for classifying substances as acids or bases.
Three main theories exist in chemistry for this purpose.
Arrhenius Theory
Brønsted-Lowry Theory
Lewis Theory
Acids and bases. Classical concept of acid and bases - Arrhenius theory.
Definition:
Proposed by Svante Arrhenius in 1884.
Provides a basic understanding of acids and bases in aqueous solutions.
Acids:
Electrolytes that dissociate in water to produce hydrogen ions (H⁺).
Examples include hydrochloric acid (HCl), sulfuric acid (H₂SO₄), etc.
Bases:
Electrolytes that dissociate in water to produce hydroxide ions (OH⁻).
Examples include sodium hydroxide (NaOH), potassium hydroxide (KOH), etc.
Ampholytes: Are Electrolytes that can act as both acids and bases. Examples include amino acids and some proteins.
Salts: Are Produced during the neutralization of an acid with a base. Example: Sodium chloride (NaCl)
Neutralization:
Process where an acid reacts with a base in water.
Results in the formation of a salt and water.
Simplified as the reaction between H⁺ ions and OH⁻ ions to form water.
Limitations:
Arrhenius theory is limited and cannot explain phenomena in non-aqueous solutions.
It doesn't account for substances that can act as acids or bases in solvents other than water.
Fails to explain the behavior of ampholytes and certain reactions in non-aqueous environments.
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