Question

What is the pH of a \( 0.001 \, \text{M} \) solution of \( \text{NaOH} \)?

• A. \( 11 \)
• B. \( 13 \)
• C. \( 10 \)
• D. \( 12 \)

Hint:

For a strong base like \( \text{NaOH} \), the concentration of \( \text{OH}^- \) ions is equal to the concentration of the base, and you can calculate pH from pOH.

Answer 1

The Correct Option is B

Step 1: Understand the relationship between pH and pOH For a strong base like \( \text{NaOH} \), the concentration of \( \text{OH}^- \) ions is equal to the concentration of the base. The pOH is given by: \[ \text{pOH} = -\log[\text{OH}^-] \] The pH and pOH are related by: \[ \text{pH} + \text{pOH} = 14 \] Step 2: Calculate the pOH Given: - Concentration of \( \text{NaOH} = 0.001 \, \text{M} \), - The concentration of \( \text{OH}^- \) ions is equal to the concentration of \( \text{NaOH} \), so \( [\text{OH}^-] = 0.001 \, \text{M} \). Now, calculate the pOH: \[ \text{pOH} = -\log(0.001) = 3 \] Step 3: Calculate the pH Now, use the relationship \( \text{pH} + \text{pOH} = 14 \): \[ \text{pH} = 14 - 3 = 11 \] Answer: Therefore, the pH of the \( 0.001 \, \text{M} \) solution of \( \text{NaOH} \) is \( 11 \). So, the correct answer is option (1).