Which one of the following processes is endothermic?
A)boiling a liquid
B)freezing a liquid
C)Condensation of gas into liquid
D)Condensation of gas into solid
You must add heat to a liquid to boil it; therefore, it is endothermic. All of the others are exothermic.
To determine which one of the processes is endothermic, we need to understand what endothermic means. Endothermic refers to a process that absorbs heat or energy from its surroundings. In other words, the process requires an input of energy to occur.
Let's evaluate each option one by one:
A) Boiling a liquid: Boiling is the process of converting a liquid into a gas by adding heat. This process requires an input of energy to break the intermolecular forces between the liquid molecules, so it is endothermic.
B) Freezing a liquid: Freezing is the process of converting a liquid into a solid by removing heat. When heat is removed, the liquid molecules slow down and form a solid structure. This process releases energy to the surroundings, making it exothermic, not endothermic.
C) Condensation of gas into a liquid: Condensation is the process of converting a gas into a liquid. This happens when the gas molecules lose energy and come together to form liquid droplets. The condensation process releases energy to the surroundings, making it exothermic, not endothermic.
D) Condensation of gas into a solid: This option is not a common phase transition process. The typical phase transition from a gas to a solid is called deposition, which involves the direct conversion of a gas into a solid without going through the liquid phase. Deposition of a gas into a solid generally releases energy to the surroundings, making it exothermic.
Based on this analysis, the correct answer is A) Boiling a liquid.