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Changes of State

Introduction to the process of matter changing between solid, liquid and gas.

Atoms Practice
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Practice Changes of State
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Watch Out for the Mold!

Watch Out for the Mold!

Credit: Kristopha Hohn
Source: http://www.flickr.com/photos/seishin17/3564681451/
License: CC BY-NC 3.0

Watch out! That’s black mold growing on the back of the wallpaper pictured above. Mold can grow in a house that has dampness issues. It may not be obvious unless you look for it, as this picture shows. But even hidden mold can make people sick.

Why It Matters

  • Mold in homes can be a serious problem. Even a relatively small amount of mold can cause allergies, asthma, and other health problems.
  • A major reason for mold growth in the home is condensation. Water vapor in the air inside the home changes state and turns into liquid water on surfaces. Condensation caused the mold growth on the wallpaper pictured above.
  • Credit: carlpenergy
    Source: https://www.flickr.com/photos/70237334@N04/6379728773
    License: CC BY-NC 3.0

    This flooded house has grown mold due to the damp atmosphere [Figure2]


  • Where does the water vapor in homes come from? Why does it condense? More importantly, how can it be prevented? Watch the following video to find out:


Show What You Know

Learn more about condensation and mold in homes at the links below. Then answer the questions that follow.

  1. What are some sources of water vapor in the home?
  2. Where does water vapor condense in a home?
  3. Compare the amount of water vapor warm indoor air can hold with the amount that cold outdoor air can hold.
  4. How can indoor condensation be prevented?
  5. Why do older homes generally have fewer condensation problems than newer homes?
  6. How does mold start growing indoors?
  7. What is the only effective way to prevent indoor mold?

Image Attributions

  1. [1]^ Credit: Kristopha Hohn; Source: http://www.flickr.com/photos/seishin17/3564681451/; License: CC BY-NC 3.0
  2. [2]^ Credit: carlpenergy; Source: https://www.flickr.com/photos/70237334@N04/6379728773; License: CC BY-NC 3.0

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