Strong Acids and Strong Bases
The seven strong acids and eight strong bases that ionize completely in water. Essential for pH calculations and acid-base reaction predictions.
| Name | Formula | Type | Dissociation in Water | Notes |
|---|---|---|---|---|
| Hydrochloric acid | HCl | Strong acid | HCl → H+ + Cl- | Most common lab acid; found in stomach acid |
| Hydrobromic acid | HBr | Strong acid | HBr → H+ + Br- | Used in organic synthesis |
| Hydroiodic acid | HI | Strong acid | HI → H+ + I- | Strongest of the hydrohalic acids |
| Nitric acid | HNO3 | Strong acid | HNO3 → H+ + NO3- | Oxidizing acid; reacts with metals below H in activity series |
| Sulfuric acid | H2SO4 | Strong acid | H2SO4 → H+ + HSO4- | Diprotic; first dissociation is strong, second is weak (Ka₂ = 0.012) |
| Perchloric acid | HClO4 | Strong acid | HClO4 → H+ + ClO4- | Strongest common acid in aqueous solution |
| Chloric acid | HClO3 | Strong acid | HClO3 → H+ + ClO3- | Strong oxidizer; less common in labs |
| Lithium hydroxide | LiOH | Strong base | LiOH → Li+ + OH- | Used in CO₂ scrubbers (spacecraft, submarines) |
| Sodium hydroxide | NaOH | Strong base | NaOH → Na+ + OH- | Lye; most common strong base in labs and industry |
| Potassium hydroxide | KOH | Strong base | KOH → K+ + OH- | Caustic potash; used in soap-making and batteries |
| Rubidium hydroxide | RbOH | Strong base | RbOH → Rb+ + OH- | Rare; follows Group 1 pattern |
| Cesium hydroxide | CsOH | Strong base | CsOH → Cs+ + OH- | Strongest Group 1 base; extremely hygroscopic |
| Calcium hydroxide | Ca(OH)2 | Strong base | Ca(OH)2 → Ca2+ + 2OH- | Slaked lime; limited solubility but fully dissociates what dissolves |
| Strontium hydroxide | Sr(OH)2 | Strong base | Sr(OH)2 → Sr2+ + 2OH- | Moderately soluble; used in sugar refining |
| Barium hydroxide | Ba(OH)2 | Strong base | Ba(OH)2 → Ba2+ + 2OH- | Used in titrations; forms clear solutions |
Important Notes
- "Strong" means the acid or base ionizes (dissociates) completely in dilute aqueous solution.
- All other acids and bases are classified as weak — they only partially ionize in water.
- Strong acids have very large Ka values (Ka → ∞), so the equilibrium lies completely to the right.
- H₂SO₄ is diprotic: the first proton dissociates completely (strong), but the second has Ka₂ = 0.012 (weak).
- Group 1 metal hydroxides are all strong bases and highly soluble. Group 2 hydroxides (Ca, Sr, Ba) are strong but have limited solubility.
- Mg(OH)₂ is NOT a strong base — it is sparingly soluble and only weakly basic in solution.