Problem 7

Question

What phase change is described by each term? Is the process endothermic or exothermic? a. sublimation b. vaporization C. fusion d. deposition

Step-by-Step Solution

Verified

Answer

a. Sublimation - endothermic, b. Vaporization - endothermic, c. Fusion - endothermic, d. Deposition - exothermic.

1Step 1: Understanding Phase Changes

Phase changes occur when a substance transitions from one state of matter (solid, liquid, gas) to another. These changes involve the absorption or release of energy, manifesting as either an endothermic or exothermic process.

2Step 2: Analyzing Sublimation

Sublimation is the process where a substance transitions directly from a solid to a gas without passing through the liquid phase. This process is endothermic as it requires energy to overcome the forces holding the particles in the solid state.

3Step 3: Analyzing Vaporization

Vaporization is the transition from a liquid to a gas. This process can occur through evaporation or boiling. Vaporization is endothermic because energy is absorbed to break the intermolecular forces in the liquid.

4Step 4: Analyzing Fusion

Fusion, also known as melting, is the phase change from solid to liquid. Fusion is endothermic since it requires energy to disrupt the organized structure of a solid to form a liquid.

5Step 5: Analyzing Deposition

Deposition is the transition from a gas directly to a solid, bypassing the liquid phase. Deposition is exothermic because energy is released as particles slow down and form a solid structure.

Key Concepts

Endothermic ProcessesExothermic ProcessesSublimationVaporizationFusionDeposition

Endothermic Processes

Endothermic processes are all about absorbing energy. When a substance undergoes an endothermic process, it takes in energy, usually in the form of heat, to facilitate a phase change. This intake of energy helps the substance overcome the attraction between its particles.

Examples of endothermic processes include sublimation, vaporization, and fusion.
These processes require energy to separate particles more apart, moving from a more ordered to a less ordered state.

In endothermic processes, you can often feel the surroundings become cooler because heat is absorbed from the environment.

Exothermic Processes

Exothermic processes release energy when a phase change occurs. This energy release often appears as heat, warming up the surrounding environment as particles come closer together.

Deposition is an example of an exothermic process.
During exothermic changes, systems lose energy as substances transition from a less ordered to a more ordered state.

The surroundings tend to become warmer as the system gives off heat to its environment.

Sublimation

Sublimation is a fascinating phase change where a solid directly transforms into a gas without passing through a liquid phase.

This process is endothermic.
Energy is crucial here as it is needed to break down the intermolecular forces keeping the solid particles together.

High energy input helps the solid particles to disperse and escape into the air as gas quickly.

Vaporization

Vaporization is the phase change from liquid to gas, and it's a process that happens in everyday life.

This process includes both evaporation and boiling.
It is endothermic.
Energy is absorbed to break intermolecular forces, allowing liquid particles to transition into a gaseous state.

Whether noticing water boiling on the stove or puddles slowly disappearing, vaporization is at play.

Fusion

Fusion, commonly known as melting, is the change of state from solid to liquid.

This transition is endothermic.
Energy absorption weakens the structure holding the solid together.

During fusion, increased energy makes particles vibrate intensely around each other until shifting into a liquid form. Ice cubes melting in the sun demonstrate this common phase change.