Butanoic Acid Contributes to the Rancid Odor of Spoiled Butter

Butanoic acid contributes to the rancid odor of spoiled butter. Calculate the acid ionization constant for butanoic acid if a 0.155 M solution is 1.15% ionized. The abbreviated structural formula for butanoic acid is CH₃CH₂CH₂COOH.

A) 5.1 *10^-3
B) 1.8 * 10^-3
C) 1.2 * 10^-2
D) 2.1 *10^-5
E) 1.5 *10^-5