Acids and Bases: Arrhenius and Bronsted-Lowry Theories, Properties, and Nomenclature

Acids and Bases

Introduction

This chapter introduces the fundamental concepts of acids and bases, focusing on their definitions, properties, nomenclature, and the differences between strong and weak acids and bases. Understanding these concepts is essential for studying chemical reactions in general, organic, and biological chemistry.

Arrhenius Acids and Bases

Arrhenius Acids

Arrhenius acids are substances that produce hydrogen ions (H+) when dissolved in water. These ions are responsible for the characteristic properties of acids.

• Definition: An Arrhenius acid increases the concentration of H+ ions in aqueous solution.

• General equation:

$\mathrm{HCl}(g) + \mathrm{H}_2\mathrm{O}(l) \rightarrow \mathrm{H}^+(aq) + \mathrm{Cl}^-(aq)$

• Properties:

  • Are electrolytes (conduct electricity in solution)

  • Have a sour taste

  • Turn blue litmus paper red

  • Can corrode some metals

Naming Acids

• Binary acids (hydrogen + nonmetal or CN-): Use the prefix hydro- and the suffix -ic acid. Example: HCl(aq) is hydrochloric acid

• Oxoacids (hydrogen + polyatomic ion):

  • If the polyatomic ion ends in -ate, change to -ic acid. Example: ClO3- (chlorate) → HClO3 (chloric acid)

  • If the polyatomic ion ends in -ite, change to -ous acid. Example: ClO2- (chlorite) → HClO2 (chlorous acid)

Table: Names of Common Acids and Their Anions

Name of Acid	Anion	Name of Anion
Hydrofluoric acid	F-	Fluoride
Hydrochloric acid	Cl-	Chloride
Hydrobromic acid	Br-	Bromide
Hydroiodic acid	I-	Iodide
Hydrocyanic acid	CN-	Cyanide
Nitric acid	NO3-	Nitrate
Nitrous acid	NO2-	Nitrite
Sulfuric acid	SO42-	Sulfate
Sulfurous acid	SO32-	Sulfite
Carbonic acid	CO32-	Carbonate
Acetic acid	C2H3O2-	Acetate
Phosphoric acid	PO43-	Phosphate
Phosphorous acid	PO33-	Phosphite

Arrhenius Bases

Arrhenius bases are substances that produce hydroxide ions (OH-) in aqueous solution.

• Definition: An Arrhenius base increases the concentration of OH- ions in water.

• General equation:

$\mathrm{NaOH}(s) \xrightarrow{\mathrm{H}_2\mathrm{O}} \mathrm{Na}^+(aq) + \mathrm{OH}^-(aq)$

• Properties:

  • Are electrolytes

  • Have a bitter, chalky taste

  • Feel slippery or soapy

  • Turn red litmus paper blue

Naming Bases

• Most common Arrhenius bases are named as hydroxides.

• Examples:

  • NaOH: sodium hydroxide

  • KOH: potassium hydroxide

  • Ba(OH)2: barium hydroxide

  • Al(OH)3: aluminum hydroxide

  • Ca(OH)2: calcium hydroxide (used in food industry and dentistry)

Characteristics of Acids and Bases

Comparison Table

Characteristic	Acids	Bases
Arrhenius	Produce H+	Produce OH-
Electrolytes	Yes	Yes
Taste	Sour	Bitter, chalky
Touch	May sting	Soapy, slippery
Litmus	Red	Blue
Phenolphthalein	Colorless	Pink
Neutralization	Neutralize bases	Neutralize acids

Key Points

• Acids produce H+ in water, taste sour, and turn blue litmus red.

• Bases produce OH- in water, taste bitter/chalky, feel slippery, and turn red litmus blue.

• Both acids and bases are electrolytes, meaning they conduct electricity in solution.

Example: Household Acids and Bases

• Acids: Vinegar (acetic acid), lemon juice (citric acid)

• Bases: Baking soda (sodium bicarbonate), household ammonia (ammonium hydroxide)

Additional info: The above content covers the introductory concepts, definitions, and nomenclature of acids and bases as per Arrhenius theory, as well as their physical and chemical properties. Further sections in the chapter would address Bronsted-Lowry theory, conjugate acid-base pairs, pH calculations, and buffer systems.