Is deposition endothermic or exothermic?

Question:

Is deposition endothermic or exothermic?

Deposition Energy Change:

The physical change from a gas to a solid is accompanied by a change in overall energy of the molecules or atoms involved. The energy change is typically a change in heat (thermal energy). Like other physical processes, deposition will involve either input or emission of thermal energy. If deposition gives off heat, it will be an exothermic process. If it takes in heat, it will be an endothermic one.

Answer and Explanation:

Deposition is an exothermic reaction whereby heat is removed from a gas at a specific pressure to the point where the gas molecules or atoms no longer have enough kinetic energy to overcome the intermolecular/interatomic attractive forces between them. When this happens, the molecules or atoms begin to clump together (nucleate) and continue to get larger and larger by the process of deposition. Carbon dioxide and iodine gases are examples of substances that can go directly from a gas state to a solid state under the correct conditions. The gases are cooled (heat is removed which is the same as heat being given off) slowly until the molecules/atoms are moving slow enough that when they collide with each other, they stay stuck to each other. So gases can go directly to solids without having to become liquids first.


Learn more about this topic:

Exothermic Reaction: Definition & Example

from General Studies Science: Help & Review

Chapter 11 / Lesson 18
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