Question

Three students A, B, and C prepared mixtures using chalk powder, common salt, and milk respectively in water. Whose mixture:
(A)- Would not leave residue on filter paper after filtration?
(B)- Would show the Tyndall effect?
(C)- Would give a transparent solution?
(D)- Would it show stability?

Answer 1

Hint: Mixture in which solute is completely soluble in the solvent and forms a clear liquid is known as a solution. A mixture in which solute is insoluble insolvent and does not form a clear solution. Clear solutions will not leave any residue after filtration. The Tyndall effect is shown by colloids.

Complete answer:
-The solution is a homogeneous mixture composed of a solute dissolved insolvent. The particles of the solution are well dissolved in the solvent that they cannot be seen by naked eyes. A clear solution is stable. The particles of solute will not allow beams of light to scatter and hence will not show the Tyndall effect. The particles of solute from the solution cannot be separated by filtration.

-The suspension is a heterogeneous mixture that contains solute particles sufficiently larger that they can either settle at the bottom or may remain floating freely in the medium. The particles of solute in a suspension may be visible to the naked eyes.

-The colloid is a phase-separated mixture, in which the particles of solute are insoluble or soluble particles are suspended throughout another substance.

-Tyndall effect is the scattering of light by the particles of the solution. It is best shown by colloids.

-A mixture of chalk powder and water forms a suspension. The mixture of chalk powder and water can be separated by condensation and evaporation. The particles of chalk powder when left undisturbed settle at the bottom. The particles of chalk powder will also scatter a beam of light passing through it.

-A mixture of common salt and water forms a clear solution. This type of solution can be separated by boiling.

-When milk is dissolved in water, it forms a homogeneous mixture by dissolving each other. The two types of liquids which can dissolve each other are called miscible liquids. Such types of liquids can be best separated by distillation.

Therefore the answers of the question are-
(A) The mixtures of common salt and milk in water being clear homogeneous solutions will not leave any residues on the filter paper.
(B) The chalk powder and water being a colloid will show the Tyndall effect as the particles of chalk will remain suspended in the liquid.
(C) The mixtures of common salt and milk being completely soluble with water will form a transparent solution.
(D) The mixtures of common salt and milk in water being a clear solution will show stability.

Note: Don’t get confused between the suspension and colloids. A suspension differs from colloids in respect of particle sizes. A colloid has a particle size of 1-1000nm in diameter while suspensions have particle size over 1000nm.