Below is a representation of an aqueous solution of a weak acid HA at equilibrium.(Each circle represents 1.0 mmol of atoms,and the volume of the box is 1.0 L.Solvent water molecules are not shown for clarity.) What is the percent ionization of HA? A)100% B)50% C)25% D)12.5% E)Cannot be calculated without knowledge of K_a

Question

Quizplus · Accepted Answer

The percent ionization of a weak acid is equal to the concentration of ionized acid divided by the initial concentration of acid, multiplied by 100%. In the given diagram, there are a total of 4.0 mmol of HA and 1.0 mmol of A-. Since HA <--> H+ + A-, the concentration of ionized acid (A-) is equal to [A-] = 1.0 mmol/L. Therefore, the percent ionization is (1.0 mmol/L)/(4.0 mmol/L) x 100% = 25%. The correct answer is C.

Below Is a Representation of an Aqueous Solution of a Weak