Learning Objectives

Electrolytes

Electrolytes are substances that form ions in solution (via ionisation or dissociation)

All substances can be categorised into one of the three strengths:

Strong electrolytes ⇒ will fully form ions in solution (strong acids and ionic substances)
Weak electrolytes ⇒ will partially form ions in solution (weak acids and NH₃)
Non-electrolytes ⇒ will not form any ions in solution (most covalent molecular substances (excluding acids or NH₃))

What's the Difference Between Ionisation and Dissociation

Ionisation occurs when covalent bonds (in covalent compounds) are broken to form ions in solution (e.g. HCl 🠒 H⁺ + Cl⁻)

Dissociation occurs when ionic bonds (in electrovalent or ionic compounds) are broken to form ions in solution (e.g. NaOH 🠒 Na⁺ + Cl⁻)

Acid and Base Strength

Acid/Base Strength is effectively the extent to which the substance will dissociate/ionise

A strong acid fully ionises in solution
A weak acid partially ionises in solution
A strong base fully reacts with water to form OH⁻
A weak base partially reacts with water to form OH⁻

Monoprotic and Polyprotic Acids

Some acids are able to donate multiple protons (H⁺ ions), these are called "polyprotic acids"

An Acid molecule contains a polar bond between a hydrogen atom and an electronegative atom. This bond is disrupted when the acid is added to water, producing a H⁺ ion.

A monoprotic acid contains just one of these bonds, as such it only produces one H⁺ ion when added to water.
Diprotic acids (such as H2SO4) contain two of these bonds, producing two H⁺ ions, while Triprotic acids produce three H⁺ ions.

Salts

Salts are:

any ionic substance that does not contain H⁺, OH⁻ or O2⁻
an ionic product derived in an acid-base reaction

Salts may be neutral, acidic or basic

neutral salts are formed from the reaction between a strong acid and a strong base; they do not hydrolyse in water
basic salts are formed from the reaction between a strong base and a weak acid; they undergo hydrolysis to produce a basic solution
acidic salts are formed from the reaction between a strong acid and a weak base; they undergo hydrolysis to produce an acidic solution