Problem 14 - An Introduction to Physical Science

Question

Choose the word or phrase that best answers the question. During which process do particles of matter release energy? A) melting B) freezing C) sublimation D) boiling

Step-by-Step Solution

Answer

B) freezing.

Step 1: Understand the Question

The question asks to identify the process in which particles of matter release energy. Here, it is crucial to understand the energy changes in different state transitions.

Step 2: Analyze Each Option

Let's carefully examine each option given and whether it involves a release (exothermic) or absorption (endothermic) of energy.

Step 3: Determine the Nature of Melting

Melting is the process where a solid changes into a liquid. This process requires the absorption of energy (endothermic). Thus, particles of matter do not release energy.

Step 4: Determine the Nature of Freezing

Freezing is the process where a liquid changes into a solid. This process involves the release of energy (exothermic) as particles settle into a more ordered state.

Step 5: Determine the Nature of Sublimation

Sublimation is the transition from a solid directly to a gas. This process requires absorption of energy (endothermic). Hence, particles of matter absorb energy, not release it.

Step 6: Determine the Nature of Boiling

Boiling is the transition from a liquid to a gas. This process also requires the absorption of energy (endothermic). Therefore, particles of matter do not release energy.

Step 7: Conclusion

Out of the four given options, freezing is the only process where particles of matter release energy. Therefore, the correct answer is B) freezing.

Key Concepts

Freezing

Freezing is the process where a liquid turns into a solid. This transition occurs when the temperature of the liquid drops below its freezing point.
During freezing, particles of matter release energy in the form of heat. This energy loss is necessary for the particles to slow down and arrange themselves into a fixed structure found in solids.
Think about water turning into ice. When water freezes, it releases heat into its surroundings, helping the water molecules to settle into a crystalline structure. Therefore, freezing is an **exothermic process** because it releases energy.

State Transitions

State transitions refer to the changes of matter from one state (solid, liquid, gas) to another. These transitions can either absorb or release energy.

• Melting: Solid to liquid, requires energy (endothermic).
• Freezing: Liquid to solid, releases energy (exothermic).
• Boiling: Liquid to gas, requires energy (endothermic).
• Condensation: Gas to liquid, releases energy (exothermic).
• Sublimation: Solid to gas directly, requires energy (endothermic).
• Deposition: Gas to solid directly, releases energy (exothermic).

Understanding these transitions helps in grasping how energy changes during different processes.

Exothermic Processes

Exothermic processes are those where energy is released into the surroundings. The temperature of the surroundings increases as the system loses energy. Examples include:

• Freezing: When a liquid solidifies, it releases heat.
• Condensation: Gaseous particles release energy to form a liquid.
• Combustion: Burning substances release energy in the form of heat and light.

All these processes ultimately result in a decrease in the internal energy of the system and an increase in the energy of the surroundings.

Energy Changes in Matter

Energy changes in matter are crucial for understanding how different materials and substances behave. These changes are mainly classified into exothermic and endothermic based on whether they release or absorb energy.

• Exothermic Processes: Release energy, causing the surroundings to become warmer. (e.g., freezing, condensation)
• Endothermic Processes: Absorb energy, causing the surroundings to become cooler. (e.g., melting, boiling)

These energy changes help explain why certain processes, like freezing, feel cold to the touch (they are releasing heat), while others, like boiling, make things hotter because they are absorbing heat.
Having a clear understanding of these energy changes helps in predicting the behavior of substances under different conditions.