[Campbell Biology P.101] The text states that a solution of pH 3 is not twice as acidic as a... | Practice Question

The text states that a solution of pH 3 is not twice as acidic as a solution of pH 6, but 1,000 times more acidic. What mathematical feature of the pH scale accounts for this significant difference in acidity?

  • A: pH values are inversely proportional to [H+].
  • B: Each pH unit represents a tenfold difference in H+ concentration.
  • C: pH values are directly proportional to [OH-].
  • D: The pH scale only applies to aqueous solutions.

Explanation

The pH scale is logarithmic. A one-unit change in pH represents a tenfold change in the hydrogen ion concentration. Therefore, a solution with pH 3 has 10^ 6-3 = 10^3 = 1,000 times higher H+ than a solution with pH 6, making it 1,000 times more acidic.