- Initial volume of HCl (V_i): 25.00 mL

- Final volume of HCl (V_f): 45.00 mL

- Concentration of HCl (C_HCl): 0.100 M

Unknown:

- Volume of NaOH added (V_NaOH)

Calculations:

1. Calculate the moles of HCl used in the titration:

Moles of HCl = Concentration (C_HCl) × Volume (V_HCl)

Moles of HCl = 0.100 M × (45.00 mL - 25.00 mL)

Moles of HCl = 0.100 M × 20.00 mL

Moles of HCl = 0.00200 mol

2. Since the reaction between HCl and NaOH is a 1:1 mole ratio, the moles of NaOH required are equal to the moles of HCl.

Moles of NaOH = Moles of HCl

Moles of NaOH = 0.00200 mol

3. Calculate the volume of NaOH added using the formula:

Volume of NaOH = Moles of NaOH (Moles of NaOH) / Concentration (C_NaOH)

Volume of NaOH = 0.00200 mol / 0.200 M

Therefore, the volume of NaOH added is 0.0100 L or 10.00 mL.