Question

An aqueous HCl solution has the pH = 5. If 1 ml of this solution is being diluted to 1 L, then predict the pH of the resulting solution.

• A. 3.98
• B. 9.02
• C. 6.02
• D. 6.98

Hint:

When diluting an acidic solution, the concentration of \( \text{H}^+ \) ions decreases, causing the pH to increase.

Answer 1

The Correct Option is C

The initial concentration of \( \text{H}^+ \) ions in the solution is determined by the pH, which is 5. Thus, the concentration of \( \text{H}^+ \) ions is: \[ [\text{H}^+] = 10^{-5} \, \text{M} \] After dilution, the new volume is 1 L, and the new concentration of \( \text{H}^+ \) ions becomes: \[ [\text{H}^+]_{\text{new}} = \frac{10^{-5} \, \text{M} \times 1 \, \text{ml}}{1000 \, \text{ml}} = 10^{-8} \, \text{M} \] The pH of the resulting solution is: \[ \text{pH} = -\log(10^{-8}) = 8 \] Thus, the resulting pH is approximately 6.02.