What kind of energy change occurs when changing 1 pound of liquid ammonia to gas?

Changing 1 pound of liquid ammonia to gas involves an endothermic process. In this context, an endothermic reaction is characterized by the absorption of heat from the surroundings. When ammonia transitions from a liquid state to a gaseous state, energy in the form of heat is required to overcome the intermolecular forces that hold the liquid molecules together.

As the liquid ammonia absorbs heat, the energy facilitates the transition into the gas phase, allowing the molecules to move freely and rapidly, which is indicative of the gaseous state. This energy absorption means that the surroundings lose some heat, which is a hallmark of an endothermic process.

The other answer choices do not accurately describe the process. An exothermic reaction would involve the release of heat, which does not occur when converting liquid ammonia to gas. There is indeed a significant energy change (absorption of heat) rather than no energy change at all, and condensation refers to a process where gas turns into liquid, which is not applicable to the phase change described in the question.