Question

When an excess and a very dilute aqueous solution of $ KI $ is added to a very dilute aqueous solution of silver nitrate, the colloidal particles of silver iodide are associated with the Helmholtz double layer

• A. $ AgI : Ag^{+} : NO_{3}^{-} $
• B. $ AgI: K^{+} : NO_{3}^{-} $
• C. $ AgI : NO_{3}^{-} : Ag^{+} $
• D. $ AgI : I^{-} : K^{+} $

Answer 1

Answer: (D)

The Helmholtz double layer contains a layer of opposite charges on the surface of colloidal particles.
$ AgNO_{3}+\underset{\text{excess}}{KI}\,\rightarrow AgI+KNO_{3} $
$ AgI+KI\rightarrow AgI : I^{-} : K^{+} $