Potentiometric Titration and pH Electrodes

A 25.0 mL sample of 0.100 M weak acid (HA, Ka = 1.8 × 10⁻⁵) is titrated with 0.100 M NaOH. (a) Calculate the pH at the half-equivalence point. (b) Calculate the pH at the equivalence point. (c) Sketch the titration curve and indicate where the buffer region is. (d) How does a glass pH electrode work? (e) What would happen to the titration curve if the acid were 100× weaker (Ka = 1.8 × 10⁻⁷)?