Question

Boiling process is a:
A) Surface phenomenon
B) Bulk phenomenon
C) Both surface and bulk phenomenon
D) Rare phenomenon

Answer 1

Hint: When a liquid phase of the substance reaches the boiling point, the bubbles formed of the gas rise into the surface and then burst into air. If the liquid gets heated more than the temperature does not rise but it boils more quickly. During this the vapor pressure gets equal to the pressure of the gas above it.


 Complete solution:
The surface phenomenon is the phenomenon in which the accumulation of a large number of molecules at the surface of the liquid phase or solid phase is more as compared to the bulk. Adsorption is also the example of surface phenomenon because in this the unbalanced or residual forces are present at the surface. Evaporation is a surface phenomenon because in this above water will evaporate from the whole water. The kinetic energy of the topmost molecules will get dissipated in air. Melting process is also an example of surface phenomenon. So boiling will not be the surface phenomenon hence option a is incorrect.
Bulk phenomenon is the phenomenon in which the whole of the substance or the compound is involved. Boiling is the bulk phenomenon because in this the particles of the bulk of liquid gain energy and then get converted into gaseous or vapor state. The heat energy is transferred to all the particles that is the entire bulk of liquid. When a liquid is boiled the heating of substance starts from the bottom of the vessel so that the temperature of the whole liquid reaches its boiling point. Hence boiling is a bulk phenomenon because everything or we can say the whole substance is affected by this.

Hence the option B is the correct answer.


Note:The process of adsorption is a surface phenomenon because the molecules which are present below the surface are attracted by other molecules from all sides. Since the surface molecules are responsible for adsorption, so it is a surface phenomenon. The extent of the process depends on the surface area of absorbent.