Question

Which inorganic precipitate in porous walls acts as a semipermeable membrane?
a.) Calcium phosphate
b.) Barium oxalate
c.) Nickel phosphate
d.) Copper ferrocyanide

Answer 1

Hint: A semipermeable membrane is membrane that permits only one constituent of the solution to pass through it, usually water, and does not permit diffusion of other constituents present in water. The inorganic precipitate which acts as a semipermeable membrane in porous walls is a complex compound having a yellow colour.

Complete answer:
We know that Semipermeable membranes, also called as selectively permeable membrane or partially permeable membrane, because they allow certain molecules or ions to pass through it.
The Vegetable membranes and animal membranes are the best examples of natural semipermeable membranes which are found just below the outer skin of the animals and plants.
Parchment paper and certain freshly prepared inorganic membranes are the examples for artificial semipermeable membranes.
Coming to inorganic semipermeable membranes, they are made up of inorganic materials and do not contain carbon moiety in its structure.
Copper Ferrocyanide precipitate is an inorganic material which acts as a best semipermeable membrane because it contains pores that are big enough for the water molecules to get through but the pores are too small to allow the bigger molecules of sugar to pass.
The molecular formula of copper ferrocyanide is \[C{{u}_{2}}[Fe{{(CN)}_{6}}]\].
So, the correct answer is “Option D”.

Additional Information:
Traube, a German chemist, established that the films of certain gelatinous precipitates, particularly of cupric ferrocyanide act as semipermeable membranes.

Note: Gelatinous precipitate is a precipitate that has a jelly-like appearance (means not solid and not liquid in nature) and it has small pores in their structure and only allows the passage of very light particles like water molecules through it.