Common Acids
- An acid is a substance that neutralises a base forming a salt and water:
2HCl(aq) + CaO(s) ⇌ CaCl2(aq) + H2O(l)
acid salt
Acids react with bases to form salt and water
- Acids are also substances that release hydrogen ions when they dissolve in water:
HCl(g) → H+(aq) + Cl– (aq)
Acids dissociate in water to release a hydrogen ion
Common Alkalis
- A base is a compound that neutralises an acid forming a salt and water
2HCl(aq) + CaO(s) ⇌ CaCl2(aq) + H2O(l)
base salt
- A base is a substance that accepts hydrogen ions or a compound that contains oxide or hydroxide ions
For example:
NH3(g) + H2O(l) → NH4+(aq) + OH–(aq)
base hydroxide ions
For example:
NaOH(s) + aq → Na+(aq) + OH–(aq)
base hydroxide ions
- A base that is soluble in water is called an alkali