Question

Consider the titration of a 23.0-ml sample of 0.105 m hc2h3O₃ (ka=1.8×10-5) with 0.120 m NaOH. Part A: Determine the initial pH.

Answer 1

To calculate the initial pH of a 0.105 M HC2H3O2 solution for titration with 0.120 M NaOH, we use the acid dissociation constant (Ka) of 1.8×10-5 and set up an ICE table to find the equilibrium concentration of H+ ions, which then allows us to determine the pH.

Step-by-step explanation:

To determine the initial pH of a 0.105 M HC2H3O2 solution (acetic acid) undergoing titration with 0.120 M NaOH, we use the acid dissociation constant (Ka) of acetic acid which is 1.8×10-5. The initial pH calculation is based on the ionization of acetic acid in water:

HC2H3O2 → H+ + C2H3O2-

The reaction set-up for the calculation of the initial pH involves creating an ICE table (Initial, Change, Equilibrium) to determine the equilibrium concentration of H+. As there's no NaOH added yet, the strong base does not affect the initial pH.

By applying the Henderson-Hasselbalch equation or directly using the Ka value in the ionization expression, one can find the concentration of H+ ions and thus the initial pH of the acetic acid solution.