Question

Homogeneous nucleation requires more undercooling than heterogeneous nucleation ___ Homogeneous nucleation usually occurs in a well-inoculated liquid ___ Heterogeneous nucleation requires less free energy for nucleation than homogeneous nucleation ___ Homogeneous nucleation commonly occurs on the surfaces of casts ___ Planar growth is promoted when the temperature of the liquid just ahead of a solid/liquid interface is larger than the melting temperature

Answer 1

Options: True or False

Answer:

(1) True

(2) False

(3) True

(4) False

Explanation: Nucleation can be described as the process that determines how long an observer has to wait before a new phase occurs,such as the conversion from liquid to gas or vapour or from Solid to liquid.

There are basically two types of Nucleation which includes the HOMOGENEOUS NUCLEATION AND THE HETEROGENEOUS NUCLEATION.

Homogeneous nucleation(nucleation that occurs in the absence of foreign particles) is a type of Nucleation that requires more undercooling than Heterogeneous nucleation, they occur below the freezing temperatures.

Heterogeneous Nucleation (a type of Nucleation that occurs in the presence of foreign particles), it usually takes place at the surface and they usually require less undercooling temperature than Homogeneous nucleation.