Properties of acids and bases

1. Definitions

✔ Arrhenius definition: Substances that produce $H^+$ (hydrogen ions) or $H_3O^+$ (hydronium ions) when dissolved in water.

✔ Brønsted-Lowry definition: Acids are proton $(H^+)$ donors.

✔ Arrhenius definition: Substances that produce $OH^-$ (hydroxide ions) when dissolved in water.

✔ Brønsted-Lowry definition: Bases are proton $(H^+)$ acceptors.

Strong acids: Ionise completely in water → High concentration of $H_3O^+.$ $H_{3} O^{+} .$
- Examples: Hydrochloric acid $(HCl)$ , Sulphuric acid $(H_2SO_4),$ Nitric acid $(HNO₃).$
Weak acids: Ionise partially in water → Lower concentration of $H_3O^+.$ $H_{3} O^{+} .$
- Examples: Ethanoic acid $(CH₃COOH)$ , Citric acid.

Strong bases: Dissociate completely in water → High concentration of $OH^-.$ $O H^{-} .$
- Examples: Sodium hydroxide $(NaOH)$ , Potassium hydroxide $(KOH).$
Weak bases: Dissociate partially in water → Lower concentration of $OH^-.$ $O H^{-} .$
- Examples: Ammonia $(NH₃),$ Calcium carbonate $(CaCO₃).$

Concentrated solution: Contains a large amount of solute per volume of water.
Dilute solution: Contains a small amount of solute per volume of water.
Strength refers to how completely an acid or base ionises/dissociates in solution.

✔ Dissociation: The process where an ionic compound splits into ions in water.

✔ Hydrolysis: The reaction of a salt with water, splitting a molecule.

✔ Amphoteric substances: Can act as both acids and bases (e.g., water $(H₂O)$ ).

✔ Equivalence point: The point where an acid completely reacts with a base.

✔ End point: The point where the indicator changes colour during a titration.

✔ Ionisation: The process where an acid or base forms ions in water.