Question

Dialysis can separate
A. Glucose and fructose
B. Glucose and sucrose
C. Glucose and NaCl
D. Glucose and proteins

Answer 1

Hint: Dialysis is one of the processes to purify the colloidal solution (impurity and colloidal particles). In this method, we place the solution in a parchment bag and this bag is made up of parchment paper which allows only the impurities to pass through itself but not colloidal particles because the bag consists of very small pours so colloidal molecules cannot pass through it as they are large. So, when this bag is placed in water, all impurities flow inside the water, and colloidal particles are left inside the bag. So this parchment paper is said to be a semipermeable membrane (which allows small molecules to pass).

Complete step by step solution:
As per the hint, it is clear that there should be impurities of very small size compared to pores in the semi-permeable membrane. Option A is the solution of glucose and fructose. As both are carbohydrates (sugar) and both are similar in size so dialysis is not a good method to separate the two as with glucose, fructose may also pass through the membrane. Sugar and sugar are separated with the distillation process (evaporation).

In option B, the solution is glucose and sucrose. Again both are sugar (carbohydrates) so to get purified sugar we use the distillation method.

In option C the given solution is of glucose and NaCl, the molecular size of glucose and \[N{{a}^{+}}\], and \[C{{l}^{-}}\]are very small due to this when its solution is poured into a parchment bag and introduced into dialysate both compounds can diffuse to dialysate (water in this case) through a semipermeable membrane.

If we talk about glucose and protein, the size of proteins is very large as compared to glucose due to this protein molecules cannot pass through the dialysis membrane and is left inside the parchment bag releasing glucose from the bag into the water. So, we can separate both the molecules from dialysis.
Thus, the correct option is D.

Additional information: Diffusion is the process of moving solute particles (solution = solute + solvent) from a high concentration of solute molecules to a low concentration of solute molecules, free of membrane. The osmosis is also used to separate molecules. In this method, one semi membrane is present(allows solvent molecules because of small size pore in membrane) through which solvent molecules flow from a less concentrated solution (less solute) to high concentrated solution (more solute) because of small size.

Note: Dialysis method is used to purify the solution contains solvent with two solutes, now these two solutes get separated through the same semi-permeable membrane (one side of membrane solvent is present and other side of membrane solvent with two solute) so this membrane allows solute molecules of small size to move toward dialysis or solvent. In this case, the solvent does not move (even small size) because the diffusion rate of one of the solutes is more than solvent.