51. A bathroom mirror fogs up during a hot shower. What is the associated phase change?
Answer: B
Condensation occurs when a bathroom mirror fogs up during a hot shower.
When steam from the hot shower comes into contact with the cooler surface of the mirror, the water vapor in the air loses energy and transforms into liquid water, which results in the fogging effect.
A) Freezing
Freezing is the process where a liquid turns into a solid when it loses energy. This option is incorrect because the fogging of a mirror does not involve any solid formation but rather the conversion of vapor to liquid.
B) Condensation
Condensation is the correct answer as it describes the process where water vapor in the air cools down and changes into liquid water droplets on the surface of the mirror. This is precisely what happens when the moisture from the steam contacts the cooler mirror surface.
C) Evaporation
Evaporation is the process where a liquid turns into a gas when it gains energy. This option is incorrect in this context because the fogging of the mirror involves the change of water vapor to liquid, not the opposite.
D) Melting
Melting refers to the transition from solid to liquid when a substance gains energy. This option is not applicable to the situation, as there is no solid involved in the fogging of a mirror; it is purely a change from vapor to liquid.
Conclusion
The correct answer is condensation, as it directly describes the phase change occurring when steam from the shower meets the cooler mirror surface, resulting in the formation of water droplets. The other options fail to apply to this scenario, as they do not involve the transition of water vapor to liquid.