Acids, Bases & Protons (Edexcel IGCSE Chemistry)

Acids, bases & protons

Proton transfer

• The earlier definition of an acid and a base can be extended
• In terms of proton transfer, we can further define each substance in how they interact with protons

Acids

• Acids are proton donors as they ionize in solution producing protons, H⁺ ions
• These H⁺ ions make the aqueous solution acidic
• Example: hydrochloric acid

HCl (aq) → H⁺(aq) + Cl^–(aq)

Bases (Alkalis)

• Bases (alkalis) are proton acceptors as they ionize in solution producing OH^- ions which can accept protons
• These OH^- ions make the aqueous solution alkaline
• Example: sodium hydroxide

NaOH (s) → Na⁺(aq) + OH^–(aq)