Questions

The perchloric acid (HClO₄) solution is more acidic. Here's why:

• Methyl orange indicator: Methyl orange is a pH indicator that changes color depending on the acidity of the solution.

  • It is red in strongly acidic solutions (pH < 3.1).
  • It is orange in moderately acidic solutions (pH around 3.1 - 4.4).
  • It is yellow in weakly acidic or neutral solutions (pH > 4.4).

• Observations:

  • The perchloric acid solution turned orange, indicating a moderately acidic pH.
  • The benzoic acid solution turned yellow, indicating a weakly acidic or less acidic pH than the perchloric acid solution.

• Acid Strength: Perchloric acid (HClO₄) is a strong acid. This means it completely dissociates in water, producing a high concentration of hydrogen ions (H⁺ or H₃O⁺), which results in a low pH (highly acidic).

• Benzoic acid (C₆H₅COOH) is a weak acid. This means it only partially dissociates in water, producing a lower concentration of hydrogen ions compared to a strong acid of the same concentration. This results in a higher pH (less acidic) than a strong acid.

Therefore, even though both solutions have the same molarity (1.0 M), the perchloric acid solution is more acidic because it is a strong acid and produces a higher concentration of H⁺ ions, leading to the orange color of the methyl orange indicator (a lower pH than the yellow color observed in the benzoic acid solution).