What is the pH of a 0.85 M HClO4 (perchlorate acid, a strong acid) solution?
The correct answer and explanation is:
The pH of a 0.85 M HClO4 (perchloric acid) solution can be calculated as follows:
Since HClO4 is a strong acid, it dissociates completely in water. This means that the concentration of hydrogen ions (H⁺) in the solution will be equal to the concentration of HClO4. Therefore, the concentration of H⁺ ions in the solution is 0.85 M.
To calculate the pH, we use the formula:
pH = -log[H⁺]
Substituting the concentration of hydrogen ions into the equation:
pH = -log(0.85)
Now, using a calculator:
pH ≈ 0.0706
Thus, the pH of the 0.85 M HClO4 solution is approximately 0.07.
Explanation:
The pH scale ranges from 0 to 14, where a pH of 7 is neutral, values less than 7 are acidic, and values greater than 7 are basic. In this case, since HClO4 is a strong acid, it dissociates fully in water, meaning that the concentration of hydrogen ions is the same as the concentration of the acid. The calculation of pH using the concentration of hydrogen ions is straightforward for strong acids.
In summary, the pH of a 0.85 M HClO4 solution is 0.07, indicating a highly acidic solution.