Question

What is the pH of a \( 0.01 \, \text{M} \) solution of \( \text{NaOH} \)?

• A. \( 12 \)
• B. \( 13 \)
• C. \( 14 \)
• D. \( 11 \)

Hint:

Remember: For strong bases, the concentration of \( \text{OH}^- \) is equal to the concentration of the base, and pH and pOH are related by \( \text{pH} + \text{pOH} = 14 \).

Answer 1

The Correct Option is C

Step 1: Use the formula for pOH
For a strong base like sodium hydroxide \( \text{NaOH} \), which dissociates completely in water, the concentration of \( \text{OH}^- \) ions is equal to the concentration of the base. The pOH is given by: \[ \text{pOH} = -\log[\text{OH}^-] \] Step 2: Calculate the pOH
Given: - Concentration of \( \text{NaOH} = 0.01 \, \text{M} \),
- Therefore, \( [\text{OH}^-] = 0.01 \, \text{M} \).
Substitute into the formula: \[ \text{pOH} = -\log(0.01) = 2 \] Step 3: Use the relation between pH and pOH We know that: \[ \text{pH} + \text{pOH} = 14 \] Substitute the pOH value: \[ \text{pH} = 14 - 2 = 12 \] Answer: Therefore, the pH of the \( 0.01 \, \text{M} \) solution of \( \text{NaOH} \) is \( 12 \). So, the correct answer is option (1).