4.2 Strong Acids & Weak Acids

• What is the pH of an aqueous solution formed by an acid?

  Less than seven
• Why do acids form aqueous solutions with a pH of less than seven?

  Because they ionize in aqueous solutions to release hydrogen ions
• What ions does hydrochloric acid dissociate into?

  H⁺ and Cl^-
• What ions does nitric acid dissociate into?

  H⁺ and NO₃^-
• What defines strong acids?

  They ionize completely in solution
• Name two examples of strong acids.

  Hydrochloric acid and nitric acid
• How do weak acids differ from strong acids in terms of ionization?

  Weak acids do not fully ionize in solution
• Give an example of a weak acid.

  Ethanoic acid
• What does it mean when the ionization of a weak acid is reversible?

  There is an equilibrium between undissociated and dissociated forms
• What does a double arrow in a chemical equation indicate?

  The reaction is reversible
• What does it mean when we say the equilibrium lies to the left for weak acids?

  There are more undissociated acid molecules than dissociated ones
• How is acid strength different from acid concentration?

  Strength refers to how much an acid ionizes, while concentration refers to the amount of acid in a volume
• What is the relationship between concentration and pH?

  As hydrogen ion concentration increases, pH decreases
• What does a decrease of one on the pH scale represent?

  An increase in hydrogen ion concentration by a factor of 10
• If the pH changes from 5 to 3, how much does the hydrogen ion concentration increase?

  By a factor of 100
• If the pH changes from 8 to 11, how does the hydrogen ion concentration change?

  It decreases by a factor of 1,000
• How can a strong acid achieve a low pH?

  By fully dissociating to release many hydrogen ions
• What must a weak acid be to achieve a low pH?

  It must be highly concentrated
• At any given concentration, how does the pH of a strong acid compare to that of a weak acid?

  A strong acid will always have a lower pH than a weak acid
• What determines the pH of a solution?

  The concentration of hydrogen ions