A 2500-ML Sample of Propionic Acid,HC₃H₅O₂,of Unknown Concentration Was Titrated with with 0.141

Multiple Choice

A 25.00-mL sample of propionic acid,HC₃H₅O₂,of unknown concentration was titrated with 0.141 M KOH.The equivalence point was reached when 43.76 mL of base had been added.What is the hydroxide-ion concentration at the equivalence point? K_a for propionic acid is 1.3 × 10^-5 at 25°C.

A) 1.5 × 10^-9 M
B) 1.0 × 10^-7 M
C) 1.1 × 10^-5 M
D) 8.3 × 10^-6 M
E) 1.1 × 10^-3 M