acid and bases
Key Properties of Acids and Bases
Acids and bases are crucial in various contexts, including industrial, household, and biological fluids.
Example: Hydrochloric acid (HCl) is a major component of gastric juice; vinegar and lemon juice are common acids at home.
Common household bases include ammonia and baking soda (sodium hydrogen carbonate).
Definitions and Reactions of Acids
Acids:
Ionize in aqueous solution to release hydrogen ions (H⁺).
H⁺ is effectively a proton, so acids are described as proton donors.
Example: HCl and HNO₃ are monoprotic acids (yield one H⁺).
Diprotic acids: Sulfuric acid (H₂SO₄) releases two H⁺ ions and ionizes in two steps:
H₂SO₄ → H⁺ + HSO₄⁻ (complete ionization)
HSO₄⁻ → H⁺ + SO₄²⁻ (partial ionization).
Acetic acid (CH₃COOH) is a weak acid with one ionizable hydrogen.
Definitions and Reactions of Bases
Bases:
Accept H⁺ ions or react with them to produce hydroxide ions (OH⁻) in water.
Common bases: Ionic compounds like NaOH, KOH dissociate to form OH⁻.
Ammonia (NH₃) acts as a base by accepting H⁺ from water, producing OH⁻ and NH₄⁺.
Strong vs. Weak Acids and Bases
Strong acids/bases: Completely ionize in solution (e.g., HCl, NaOH).
Weak acids/bases: Partially ionize (e.g., NH₃, HF).
Reactivity depends on H⁺ concentration and the nature of the anion.
Example: HF is weak but highly reactive with materials like glass due to HF pair reactivity.
Electrolytes and Their Behavior
Strong electrolytes: Usually ionic compounds that fully dissociate in solution.
Example: All strong acids are strong electrolytes.
Weak electrolytes: Partially dissociate or ionize in a solution.
Identification dependent on whether a compound is ionic or molecular:
Ionic = Strong electrolyte.
Molecular = Assess as acid/base: use H or COOH to determine.
Characteristics of Acids and Bases
Acids taste sour; bases taste bitter.
Indicator effects:
Acids and bases alter dye colors differently, utilized in pH indicators like litmus paper.
Neutralization Reactions
Mixing an acid and a base typically results in a neutralization reaction:
Example reaction: HCl (aq) + NaOH (aq) → H₂O (l) + NaCl (aq).
Neutralization yields water and a salt, any ionic compound where cation comes from a base and anion from an acid.
Net Ionic Equation: H⁺ + OH⁻ → H₂O.
Reactions Leading to Gas Formation
Acids reacting with certain bases can produce gases:
Example with sulfide: 2 HCl + Na₂S → H₂S (g) + 2 NaCl (aq).
Example with carbonates: HCl + NaHCO₃ → NaCl + H₂CO₃; H₂CO₃ decomposes to CO₂ (g) + H₂O (l).
Application of Acids and Bases in Everyday Life
Bases like NaHCO₃ are used as antacids to alleviate stomach acidity, reacting with H⁺ to produce CO₂ gas.
Sodium carbonate also neutralizes acid spills, stopping the fizz of CO₂ breakout as the reaction reaches completion.