(a) How does the average kinetic energy of molecules compare...

Name: Problem 10, Chapter 11: Chemistry The Central Science
Uploaded: 2021-08-26T01:36:03-08:00
Channel: David Collins
Description: (a) How does the average kinetic energy of molecules compare with the average energy of attraction between molecules in solids, liquids, and gases? (b) Why does increasing the temperature cause a solid substance to change in succession from a solid to a liquid to a gas? (c) What happens to a gas if you put it under extremely high pressure?

(a) How does the average kinetic energy of molecules compare with the average energy of attraction between molecules in solids, liquids, and gases? (b) Why does increasing the temperature cause a solid substance to change in succession from a solid to a liquid to a gas? (c) What happens to a gas if you put it under extremely high pressure?

Key Concepts

Intermolecular Forces

Intermolecular forces, which are the attractive forces between molecules, determine how closely molecules are held together in different states of matter. In solids, these forces are very strong, holding molecules in fixed positions. In liquids, they are still significant but allow more movement, and in gases, they are very weak, with molecules moving freely most of the time.

Kinetic Energy of Molecules

The average kinetic energy of molecules is directly related to temperature. It reflects the energy due to molecular motion and increases as temperature increases. In gases, kinetic energy dominates since intermolecular attractions are minimal, while in solids and liquids, kinetic energy is balanced with intermolecular attractions.

Phase Transitions

Phase transitions occur when thermal energy (kinetic energy) increases sufficiently to overcome intermolecular attractions. As temperature rises, solids (with strong bonds) melt into liquids and eventually liquids vaporize into gases, where the molecules have enough energy to break free from each other.

Pressure Effects on Gases

Under high pressure, gas molecules are forced closer together, which can enhance intermolecular interactions even in gases. This can lead to conditions where the gas behaves more like a liquid and, at extremely high pressures, may even undergo phase changes due to the increased molecular proximity.

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