Question

2. Describe the following phases in terms of the kinetic and potential energy of the molecules in the phases. Be sure to indicate whether the kinetic or potential energy of the molecules plays a greater role in the behavior of the molecules in each phase. a. Gas phase b. Solid phase 3. Explain how the kinetic molecular theory concept of elastic collisions between molecules might not be the best description especially for liquids and solids.

Answer 1

Solution:

2) During a phase transition, when kinetic energy increases, the value of potential energy decreases and vice versa. The potential energy predominates over kinetic energy when molecules are arranged properly while kinetic energy predominates over potential energy when molecules are arrange far apart from each other.

Thus,

Gas phase : In gas phase, the arrangement of atoms or molecules are random hence kinetic energy playing the important role.

KE = 1/2 m v^2

Kinetic energy increases with increasing velocity and velocity increases with temperature.

Solid phase:

Potential energy playing important role in solid phase because it increases with increasing proper arrangment.

PE = m g h

3) According to kinetic gas theory, there is a collision take place between gas molecules and this collision is assumed to be elastic because gas molecules are considered as tiny small paricles and intermolecular attraction is very weak.

These assumptions are not applicable for solids and liquids because they posses strong intermolecular attraction, hence collision can never be elastic.