Question

Butyric acid is responsible for the odor in rancid butter. A solution of 0.25 M butyric acid has a pH of 2.71. what is the Ka for the acid?

Can you please show me how to set this up with an ICF/ICE table. I know the (Ka x AC)^0.5 but our prof said we must do it the ICE/ICF way I don’t under stand why the concentration of hydronium ions are squared?

Answer 1

To calculate the Ka for butyric acid, you can use the given pH value and set up an ICE table to calculate the concentration of H^+. Using this concentration, you can then calculate the Ka value of butyric acid.

Step-by-step explanation:

To calculate the Ka for butyric acid, we can use the information given about its pH. The equation for the dissociation of a weak acid is CH3CH2CH2COOH(aq) → CH3CH2CH2COO^-(aq) + H^+(aq). We can set up an ICE table to calculate the concentration of H^+.

The initial concentration of butyric acid is 0.25 M, so the initial concentration of H^+ is 0 M. Since the concentration of H^+ is small compared to the initial concentration of butyric acid, we can assume that the change in concentration of butyric acid is approximately equal to the change in concentration of H^+. Let's call both of these values x.

The final concentration of butyric acid is 0.25 - x M, and the final concentration of H^+ is x M. Using the pH value of 2.71, we can calculate x and then use it to calculate the concentration of H^+ and the Ka value of butyric acid.