Question

Which of the following processes is endothermic? A) Freezing water B) Combustion of gasoline C) Condensation of steam D) Burning wood

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Answer 1

• The correct answer is C) Condensation of steam ✅

➱ It is an endothermic process as it involves the release of heat energy from steam to its surroundings, causing the steam to cool and change into liquid water.

Step-by-step explanation:

Condensation is the process by which a vapor or gas changes into a liquid state. When steam (water vapor) condenses, it releases energy in the form of heat to its surroundings. This energy is absorbed by the vapor's molecules as they slow down and come closer together, forming liquid water molecules.

Here's a step-by-step explanation of why condensation is endothermic:

• Steam is composed of water molecules in a gaseous state. These molecules have a relatively high amount of kinetic energy due to their fast movement.
• As steam comes into contact with a colder surface or a colder environment, its molecules lose energy. This energy is released as heat, which warms up the surrounding environment.
• The loss of kinetic energy causes the water vapor molecules to slow down and come closer together. This change in molecular arrangement leads to the formation of liquid water.
• The energy that was initially present as kinetic energy in the steam is now absorbed by the surrounding environment to facilitate the phase change from a gaseous state to a liquid state.
• The process of condensation causes a decrease in the temperature of the steam and its surroundings. This is because the heat energy is being used to break the intermolecular bonds in the gas (steam) and form new bonds in the liquid (water).

Answer 2

The correct answer is C) Condensation of steam. It is an endothermic process because it involves the release of heat energy as steam changes into liquid water.

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✴ Let's delve into the details of each process to understand why C) Condensation of steam is the correct answer:

A) Freezing Water:

When water freezes, it changes from a liquid state to a solid state (ice). During this process, heat energy is released, causing the molecules to slow down and arrange themselves into a structured pattern. This release of heat makes the freezing process exothermic, not endothermic.

B) Combustion of Gasoline:

The combustion of gasoline involves the reaction of gasoline with oxygen to produce carbon dioxide, water vapor, and energy in the form of heat and light. This process is highly exothermic, as it releases a significant amount of heat energy.

D) Burning Wood:

Similar to the combustion of gasoline, burning wood also involves the release of energy in the form of heat and light. As wood burns, the energy stored in its chemical bonds is released, making this process exothermic.

C) Condensation of Steam:

Condensation is the process by which a vapor or gas changes into a liquid as it loses heat energy. When steam (water vapor) condenses, it changes from a high-energy gaseous state to a lower-energy liquid state. This transition requires the input of heat energy to break the intermolecular forces holding the water molecules in the vapor state. The absorbed heat energy doesn't raise the temperature but is used to overcome the attractive forces between molecules, allowing them to come together as liquid water. Thus, the condensation of steam is an endothermic process.