What volume (in mL) of $0.1 M$ $NaOH$ must be added to $100 mL$ of $0.2 M$ $HCl$ so that the pH of the final solution is exactly 2.00? Give the answer to the nearest integer.

Numerical answer type, answer in mL, tolerance 1.

Answer: 173 mL

Let the volume of

NaOH

V

mL. Excess

H X^{+}

= 20 - 0.1 V

mmol in

(100 + V)

mL must equal

1 0^{- 2}

20 - 0.1 V = 0.01 (100 + V)

. So

19 = 0.11 V

and

V = 172.7 \approx 173 mL