(a) How does the average kinetic energy of molecules com- pare with the average energy of attraction between mole- cules in solids, liquids, and gases?

Key Concepts

Kinetic Molecular Theory

The Kinetic Molecular Theory explains the behavior of gases in terms of the motion of their molecules. It posits that gas molecules are in constant, random motion and that the temperature of a gas is directly proportional to the average kinetic energy of its molecules. This theory helps to understand how kinetic energy varies in solids, liquids, and gases, influencing their physical properties.

Intermolecular Forces

Intermolecular forces are the attractive forces between molecules that influence the physical state of a substance. In solids, these forces are strong, keeping molecules closely packed; in liquids, they are moderate, allowing for some movement; and in gases, they are weak, resulting in free movement of molecules. Understanding these forces is crucial for comparing them to kinetic energy in different states of matter.

Phase Changes

Phase changes refer to the transitions between solid, liquid, and gas states, which occur due to changes in temperature and pressure. During these changes, the balance between kinetic energy and intermolecular forces shifts, affecting the average energy of attraction. For instance, as a solid melts into a liquid, the kinetic energy increases, overcoming some intermolecular forces, which is essential for understanding the energy dynamics in different phases.