Question

Evaporation is accompanicd by (1) absorption of heat (2) evolution of heat (3) Neither absorption nor evolution of heat (4) either absorption or evolution of heat

Short answer

The correct answer is (1) absorption of heat.

Step-by-step solution

Understand Evaporation

Evaporation is the process by which molecules in a liquid state gain enough energy to enter the gaseous state.

Energy Requirement for Evaporation

For molecules to transition from liquid to gas, they need to absorb energy. This energy is typically absorbed from the surrounding environment in the form of heat.

Determine the Correct Option

Given that evaporation involves molecules in a liquid gaining energy (heat) to become gas, the correct option is the one that mentions 'absorption of heat'.

Select the Correct Answer

Based on the understanding, the correct answer is (1) absorption of heat.

Key concepts

heat absorption

When we talk about evaporation, one of the main things happening is the absorption of heat. This means that for a liquid to turn into a gas, it needs to take in energy. Where does this energy come from? It comes from the surroundings. For example, when you sweat and the sweat evaporates off your skin, it absorbs heat from your body, making you feel cooler.

In essence, heat is a form of energy transfer. When molecules in a liquid absorb this heat, their energy levels go up. They start moving faster and faster until some of them move so fast that they can escape into the air as gas. This whole process highlights the importance of heat absorption in evaporation.

Another good example is boiling water. If you boil water, heat from the stove is absorbed by the water. This added heat gives the water molecules the energy they need to turn into steam and float away.

energy transition

Energy transition refers to the change in energy states of molecules during evaporation. When a liquid evaporates, it's because the molecules have gained enough energy to change from one state to another—from liquid to gas. This energy transition is crucial for the evaporation process.

Think of it this way: imagine the molecules in the liquid are at a party. They start off slow, just kind of swaying around. As they absorb more heat (just like people getting excited with the right music), they start jumping and moving faster. Eventually, some of them 'jump' so much that they leave the party. This 'jumping' out of the liquid and into the air represents the energy transition.

So, without the energy transition, the molecules in a liquid would never get the energy boost they need to become gas. This concept helps explain why evaporation can't happen unless there's an input of energy.

liquid to gas

Evaporation is all about the change from liquid to gas. This phase transition is one of the key aspects of the water cycle on Earth. When you observe puddles of water on a sunny day, and then they disappear, this is because of evaporation.

For a liquid to turn into a gas, it must overcome intermolecular forces—the forces that hold the molecules together. Heat provides the energy required to break these bonds, allowing molecules to separate and move freely as gas.

This transition isn’t just limited to water. It applies to all liquids. For example, alcohol evaporates faster than water because its molecules require less energy to overcome intermolecular forces. Understanding this transition from liquid to gas can help you grasp how different substances interact with heat and how they behave in different environments.