The following pictures represent solutions that contain a weak acid HA (pK_a = 5.0) and its potassium salt KA.Unshaded spheres represent H atoms,black spheres represent oxygen atoms,and shaded spheres represent A^- ions.(K⁺,H₃O⁺initially present,OH^-initially present and solvent water molecules have been omitted for clarity. )
-Which picture represents the equilibrium state of the solution after addition of one OH^- ion to the solution shown in picture (1) ?

Question

The following pictures represent solutions that contain a weak acid HA (pK_a = 5.0) and its potassium salt KA.Unshaded spheres represent H atoms,black spheres represent oxygen atoms,and shaded spheres represent A^- ions.(K⁺,H₃O⁺initially present,OH^-initially present and solvent water molecules have been omitted for clarity. )

The following pictures represent solutions that contain a weak acid HA (pK<sub>a</sub> = 5.0) and its potassium salt KA.Unshaded spheres represent H atoms,black spheres represent oxygen atoms,and shaded spheres represent A<sup>-</sup> ions.(K<sup>+</sup>,H<sub>3</sub>O<sup>+ </sup>initially present,OH<sup>- </sup>initially present and solvent water molecules have been omitted for clarity. ) -Which picture represents the equilibrium state of the solution after addition of one OH<sup>-</sup> ion to the solution shown in picture (1) ? A) (2) B) (3) C) (4) D) (5)

-Which picture represents the equilibrium state of the solution after addition of one OH^- ion to the solution shown in picture (1) ?

Quizplus · Accepted Answer

When one OH^- ion is added, it reacts with the weak acid HA to form its conjugate base A- and water (HA + OH^- → A- + H2O). This shift in the equilibrium will cause more HA to dissociate to form A- ions and H+ ions, and according to Le Chatelier's principle, the equilibrium will shift towards the side with fewer H+ ions. Thus, the equilibrium state will have more A- ions and fewer H+ ions, which is represented in picture (3).

The Following Pictures Represent Solutions That Contain a Weak Acid