The following pictures represent solutions that contain a weak acid HA and/or its potassium salt KA.Unshaded spheres represent H atoms and shaded spheres represent A - ions.(K + ,H 3 O + ,OH - ,and solvent H 2 O molecules have been omitted for clarity. )
-Which solution has the greatest buffer capacity?
A)(1)
B)(2)
C)(3)
D)(4)

Question

The following pictures represent solutions that contain a weak acid HA and/or its potassium salt KA.Unshaded spheres represent H atoms and shaded spheres represent A - ions.(K + ,H 3 O + ,OH - ,and solvent H 2 O molecules have been omitted for clarity. ) 
-Which solution has the greatest buffer capacity?
A)(1) 
B)(2) 
C)(3) 
D)(4)

Quizplus · Accepted Answer

Buffer capacity is greatest when the pH of the solution is equal to the pKa of the acid in the buffer system, as this is when there is an equal concentration of the acid and its conjugate base, allowing the buffer to effectively neutralize added acids or bases.

The Following Pictures Represent Solutions That Contain a Weak Acid