Acid-Base Titrations Practice Test

A student titrates $30.0,\text{mL}$ of $0.100,\text{M}$ HF ($K_a=6.8\times 10^{-4}$) with $0.100,\text{M}$ NaOH. At the equivalence point, which species is primarily responsible for determining the pH of the solution?

A student titrates $40.0\ \text{mL}$ of $0.100\ \text{M}$ HCOOH (formic acid, $K_a=1.8\times10^{-4}$; $pK_a\approx 3.74$) with $0.100\ \text{M}$ NaOH. After $20.0\ \text{mL}$ of NaOH is added, what is the pH? (Use Henderson–Hasselbalch.)