• 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

Names & formulae of some common acids table

• In organic acids (such as carboxylic acids) only some of the hydrogen atoms can form ions when the acid dissociates

• 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

Names & formulae of some common alkalis table