Question

Does chalk powder dissolve in water or not?

Answer 1

Hint : Chalk powder is formed from calcite which is the mineral form of calcium carbonate. The solubility of calcium carbonate can be determined by recalling the trends of decreasing or increasing solubility of alkaline earth metal carbonates.

Complete Step By Step Answer:
A suspension solution is heterogeneous in nature and is formed when the particle size is not small enough to get evenly distributed throughout the bulk. In such solutions the particles settle down at the bottom of the container when the solution is made to stand still (no stirring done) due the force of gravity acting upon the large sized particles. The substances forming a suspension solution in water is a consequence of their limited solubility.
Examples of suspension include mud or flour in water.
The alkaline earth metals like beryllium, magnesium and calcium tend to have very low solubility in water. The solubility of these ionic compounds is influenced by the extent of hydration and the hydration enthalpies being released.
Thus chalk powder made up of calcium carbonate ${\text{(CaC}}{{\text{O}}_3})$ does not dissolve completely in water and forms a suspension.

Additional Information:
Suspensions like colloidal solutions can show Tyndall effect provided that a large number of particles remain suspended in the solution for a considerable amount of time.
The suspension solution can become completely opaque if the particles are too large and coloured.

Note :
Colloidal solutions are different from suspension solutions in terms of particle size. Colloidal solutions have smaller particles that do not settle down due to gravity like those of a suspension solution. Simple filtration can be used to separate the constituents of a suspension.