Strong vs Weak Acids 201 Chemistry

NaCl(s) Na+(aq) + Cl-(aq) Dissociation Dissociation (ionisation) is when an ionic solid breaks up into its ions when in solution NaCl(s) Na+(aq) + Cl-(aq)

HCl(g) + H2O(l) H3O+(aq) + Cl-(aq) Strong Acids Readily donate protons Become fully dissociated HCl(g) + H2O(l) H3O+(aq) + Cl-(aq) Solution contains, H2O molecules, H3O+ and Cl- ions and no HCl molecules

CH3COOH(aq) + H2O(l) CH3COO-(aq) + H3O+(aq) Weak Acids Limited proton donation Only partially dissociates CH3COOH(aq) + H2O(l) CH3COO-(aq) + H3O+(aq) Solution contains mostly H2O and CH3COOH molecules and only a few CH3COO- and H3O+ ions

NaOH(s) Na+(aq) + OH-(aq) Strong Bases Readily accepts protons Becomes completely dissociated NaOH(s) Na+(aq) + OH-(aq)

NH3(aq) + H2O(l) NH4+(aq) + OH-(aq) Weak Bases Limited proton accepting Only partially dissociates NH3(aq) + H2O(l) NH4+(aq) + OH-(aq)

Dilute & Concentration Concentrated acids contain more H3O+ ions Concentrated bases contain more OH- ions

Concentration vs Strength Concentration refers to amount H3O+/OH- ions at a given volume. Strength refers to the ease a substance will undergo proton transfer

Conductivity Strong acids fully dissociate into charged ions therefore are excellent conductors of electricity HA(g) + H2O(l) → H3O+(aq) + A-(aq) Weak acids are only partially dissociated therefore are poor conductors of electricity HA1(aq) + H2O(l) ↔ H3O+(aq) + A1-(aq)

pH Weak acids have a higher pH than strong acids of the same concentration as the actual concentration of H3O+ is less. This is because most of the acid remains in the molecular form.

Rate of Reaction Strong acids fully dissociate therefore there is a higher concentration of H3O+ ions which leads to a faster rate of reaction HA(g) + H2O(l) → H3O+(aq) + A-(aq) Weak acids are only partially dissociated most of the acid remains in its molecular form. There is a lower concentration of H3O+ ions so a slower rate of reaction HA1(aq) + H2O(l) ↔ H3O+(aq) + A-(aq)

HA(aq) + H2O(l) ↔ H3O+(aq) + A-(aq) Extent of Reaction Even though weak acids are only partially dissociate it is in equilibrium. As a reaction proceeds (the H3O+ is used/removed) the equilibrium favours the forwards reaction and more h3o+ is made. The reaction continues until either the acid or other reactant is used up. HA(aq) + H2O(l) ↔ H3O+(aq) + A-(aq)