1. Strengths of Acids and Bases

2.  Acids and bases are classified as strong or weak according to the degree to which they ionize in water.  Strong acids are completely ionized in aqueous solution.  Examples: Hydrochloric acid and sulfuric acid.  HCl(g) + H 2 O(l) → H 3 O + (aq) + Cl - (aq)  HCl dissociates completely (100%) into ions when dissolved in water.

3.  Weak acids ionize only slightly in aqueous solution.  Example: Acetic (ethanoic) acid  CH 3 COOH(aq) + H 2 O(l) ⇄ H 3 0 + (aq) + CH 3 COO - (aq)  The ionization is not complete.  The same principle is true for strong bases and weak bases.

4.  The strength or weakness of an acid or base ( the degree of ionization that occurs) is independent of its concentration.  The words concentrated and dilute refer to how much of an acid or base is dissolved in solution.  When you have a dilute solution of hydrochloric acid, it is still a strong acid (gastric juice).  Vinegar (acetic acid) is a dilute solution of a weak acid…a sample of pure acetic acid would still be a weak acid.

5.  Salts consist of an anion from an acid and a cation from a base.  Some salt solutions may be acidic or basic, but many are neutral (NaCl).  In general, salts that produce acidic solutions contain positive ions that release protons to water. Salts that produce basic solutions contain negative ions that attract protons from water.