Proton Transfer Reactions & Acid-Base Behaviour (IB HL)

Bronsted-Lowry Acid

Proton (H⁺) donor

Bronsted-Lowry Base

Proton (H⁺) acceptor

Conjugate Acid

Species formed after a base accepts a proton

Conjugate Base

Species formed after an acid donates a proton

Amphiprotic

Substance that can act as both a proton donor and acceptor

Amphoteric

Substance that can act as both an acid and a base

Example of amphiprotic species

H₂O or HCO₃⁻

Strong acid

Completely dissociates in water (e.g. HCl, HNO₃)

Weak acid

Partially dissociates in water (e.g. CH₃COOH)

Strong base

Completely dissociates in water (e.g. NaOH)

Weak base

Partially dissociates in water (e.g. NH₃)

Reaction: Acid + Base →

→ Salt + Water

Reaction: Acid + Metal →

→ Salt + Hydrogen gas

Reaction: Acid + Carbonate →

→ Salt + CO₂ + H₂O

Reaction: Acid + Ammonia →

→ Ammonium salt

What does pH indicate?

Strength of acid or base (lower pH = stronger acid)

How does conductivity relate to strength?

More ionisation = higher conductivity = stronger acid/base

How do you identify conjugate pairs?

Look for species differing by one H⁺