Calculate the pH of 0.046 M HClO4.
The correct answer and explanation is:
The pH of a solution can be calculated using the formula: pH=−log[H+]\text{pH} = -\log[\text{H}^+]
where [H+][H^+] is the concentration of hydrogen ions in the solution.
For a strong acid like HClO4HClO_4 (perchloric acid), it dissociates completely in water. This means that the concentration of hydrogen ions ([H+][H^+]) will be equal to the concentration of the acid itself. Therefore, for a 0.046 M solution of HClO4HClO_4, the concentration of H+H^+ ions will also be 0.046 M.
Now, substituting this value into the pH formula: pH=−log(0.046)\text{pH} = -\log(0.046)
Using a calculator: pH=1.337\text{pH} = 1.337
Therefore, the pH of a 0.046 M HClO4HClO_4 solution is approximately 1.34.
Explanation:
The pH scale measures the acidity or alkalinity of a solution. It is a logarithmic scale based on the concentration of hydrogen ions in the solution. Strong acids like HClO4HClO_4 dissociate fully in water, meaning that all of the acid molecules release hydrogen ions (H+H^+) into the solution. This results in a higher concentration of hydrogen ions and a lower pH.
The pH scale ranges from 0 to 14, with values below 7 indicating acidity, values above 7 indicating alkalinity, and 7 being neutral. Since the concentration of hydrogen ions in a 0.046 M HClO4HClO_4 solution is relatively high, the pH is below 7, confirming that the solution is acidic.