Question

What is the pH of a 0.01 M solution of $ \text{HCl} $?

• A. \( 2 \)
• B. \( 4 \)
• C. \( 1 \)
• D. \( 3 \)

Hint:

Remember: For strong acids like \( \text{HCl} \), the concentration of \( \text{H}^+ \) ions is equal to the concentration of the acid in solution.

Answer 1

The Correct Option is A

Step 1: Recall the formula for pH
The pH of a solution is calculated using the formula: \[ \text{pH} = -\log[\text{H}^+] \] where \( [\text{H}^+] \) is the concentration of hydrogen ions.
Step 2: Use the concentration of \( \text{HCl} \)
Hydrochloric acid (\( \text{HCl} \)) is a strong acid and dissociates completely in water: \[ \text{HCl} \rightarrow \text{H}^+ + \text{Cl}^- \] Therefore, the concentration of \( \text{H}^+ \) ions is equal to the concentration of \( \text{HCl} \), which is \( 0.01 \, \text{M} \).
Step 3: Calculate the pH
Substitute the concentration of \( \text{H}^+ \) into the pH formula: \[ \text{pH} = -\log(0.01) = 2 \]
Answer:
Therefore, the pH of the 0.01 M \( \text{HCl} \) solution is \( 2 \). So, the correct answer is option (1).