Question

Observe and Infer You take a hot shower. The mirror in the bathroom fogs up. Infer from this information what has happened.

Short answer

The mirror fogs due to condensation from water vapor in the steamy air.

Step-by-step solution

Understand the Scenario

You take a hot shower in a bathroom and notice that the mirror becomes fogged.

Observe the Effects of Hot Water

When the hot water is used during a shower, it evaporates into the air, increasing the humidity in the bathroom.

Condensation on a Cooler Surface

The mirror is cooler compared to the warm, humid air. When the warm, moist air comes in contact with the cooler surface of the mirror, the water vapor condenses, forming droplets.

Conclusion

The foggy appearance on the mirror is due to condensation, where the water vapor in the air changes back into liquid water upon touching a cool surface.

Key concepts

Humidity

When you take a shower, especially with hot water, humidity rises in the bathroom. Humidity is the amount of water vapor present in the air. This happens because the hot shower adds moisture, making the air feel damp and heavy.

High humidity can make it difficult for sweat to evaporate from our skin, leading to a feeling of discomfort. Items like mirrors can become foggy as they encounter humid air, as it often leads to the next process, condensation. In short, humidity reflects the level of saturation in the air caused by the presence of water vapor.

Water Vapor

Water vapor is the gaseous form of water. It naturally occurs in the atmosphere from various sources like lakes, rivers, and while taking a shower. During a shower, the hot water generates steam, which then becomes water vapor.

Water vapor is invisible; however, you might see it as steam. In the shower scenario, this water vapor causes increased humidity. When conditions change, such as the temperature, it may turn back into liquid, causing things like a foggy mirror. Understanding its dynamics is essential for grasping how environmental changes affect weather and climate.

Evaporation

Evaporation is the process where liquid water turns into water vapor. It requires energy, usually in the form of heat, which is why hot showers are significant in this context.

• When the shower water heats up, it causes water molecules to move faster.
• Some molecules gain enough energy to escape into the air, thus becoming water vapor.

This increased energy and molecular movement contribute to the overall rise in humidity. Evaporation is a reversible process and forms an integral part of the water cycle on Earth.

Temperature Difference

A temperature difference occurs when two surfaces, or areas, have different temperatures. In the bathroom, this is evident between the warm air from the shower and the cooler mirror.

• Warm air absorbs more moisture, carrying it as water vapor.
• The mirror, being cooler, causes this vapor to cool down and change to liquid, forming droplets.

This cooling effect is the essence of condensation. It’s a clear demonstration of how varying temperatures can influence physical states of water, transforming it from an invisible vapor to visible droplets on surfaces.