Question
On a cold day,droplets of water form on a cold window. Explain how these droplets form. __
Answer
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Llinos
Master · Tutor for 5 years
Answer
Droplets form on a cold window due to the process of condensation. When the warm air inside the room, carrying moisture, comes into contact with the colder window, it loses its ability to hold as much moisture. As a result, the excess moisture gets deposited on the window in the form of liquid droplets.
Explanation
The question deals with a basic natural process that occurs due to the physical properties of water and temperature differences, more specifically the concept of condensation. When it's colder outside than inside, the inside air can hold more moisture. This moisture will come from many sources within a building, like people's breath, cooking, showering, or from plants. This air will diffuse in the whole room volume constantly returning to homogeneity if disrupted. Upon contact with a cold window, where the temperature might be the same or other times even colder as the one outside, the air near the window cools down by thermal transfer (conduction) through the window. As it cools, it loses its capacity to hold as much moisture. Thus, the excess water gets deposited as liquid are onto the cooler surface mainly due to the relocation from air.This is a process called the condensation phase change, where water vapor becomes liquid water droplets on the window surface.