Chemistry: Acids and Bases Overview

Acids and Bases

• Acids and bases exhibit various physical and chemical properties.
• The hydronium ion (H₃O⁺) forms when water reacts with an acid.
• Acids and bases are classified using the Arrhenius, Brønsted-Lowry, and Lewis models.

Acid and Base Strength and Concentration

• Acid strength differs from concentration.
• Strong acids completely ionize in solution, while weak acids only partially ionize.
• Concentrated acids contain a high amount of solute per unit volume, diluted acids contain a low amount.
• Monoprotic acids donate one proton, diprotic donate two, and polyprotic acids donate more than two protons

pH

• pH measures the concentration of hydrogen ions (H⁺) in a solution.
• pOH measures the concentration of hydroxide ions (OH⁻) in a solution.
• The pH scale ranges from 0 to 14, with 7 being neutral.
• pH is calculated using the formula pH= -log[H⁺]
• pOH is calculated using the formula pOH= -log[OH⁻]

Neutralization

• Acid-base reactions produce a salt and water.
• Neutralization is a double-replacement reaction.
• A salt is formed from a cation from a base and anion from an acid.

Titration

• Titration is a technique for determining the concentration of an unknown solution.
• A known concentration (titrant) is used to react with a known volume of unknown solution.
• The equivalence point in a titration is the point where the moles of H⁺ from the acid equals the moles of OH⁻ from the base.
• An abrupt change in pH occurs at the equivalence point.
• The formula cbMaVa = caMbVb is important in titration calculations. Where cb = concentration of base, ca = concentration of acid, Ma = molarity of acid, Mb = molarity of base, Va = volume of acid, Vb = volume of base.

Additional Notes

• Indicators are used to mark the end point of a titration.
• Different indicators change color at different pH values.
• Water is a universal solvent for acids and bases and undergoes self-ionization. The reaction is H₂O(l) + H₂O(l) ⇌ H₃O⁺(aq) + OH⁻(aq).

Lewis Model

• A Lewis acid accepts a pair of nonbonding electrons.
• A Lewis base donates a pair of nonbonding electrons.