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Introduces solutions and solubility followed by examples of common solutions.

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Get the Salt Out

Get the Salt Out

Credit: Nina Matthews Photography
Source: http://www.flickr.com/photos/21560098@N06/7525248148
License: CC BY-NC 3.0

The ocean extends as far as the eye can see. Water, water everywhere, but there’s not a drop to drink. That’s because seawater is too salty to consume.

Why It Matters

  • Of all Earth’s water, almost 97 percent is salty ocean water that we can’t drink. Only about 1 percent of Earth’s liquid water is freshwater available for human needs.
  • There is increasing scarcity of fresh drinking water in many parts of the world as the human population grows. By 2030, almost half the world’s population will live in regions where water is scarce.
  • Credit: eutrophication&hypoxia
    Source: https://www.flickr.com/photos/48722974@N07/4538714228
    License: CC BY-NC 3.0

    Human populations are rapidly growing while water is becoming scarce [Figure2]

  • About 40 percent of the human population lives near an ocean. If we could drink seawater, most of our water problems would be solved.
  • Actually, we can drink seawater. At least, we can if the salt is removed. Watch this video to see how this can be done: 


What Do You Think?

Learn more about getting the salt out of ocean waterat the link below. Then answer the questions that follow.

  1. What is desalination? Briefly describe two general methods of desalination.
  2. What is osmosis? Osmosis requires a semipermeable membrane. What does this mean?
  3. What is reverse osmosis? Why does it require an input of energy?
  4. Outline the steps in desalination of water in a plant that uses reverse osmosis.
  5. The pros of desalination of ocean water to produce fresh drinking water are obvious: more water and fewer people running out of water. What are the cons of desalination?
  6. What do you think? Do the pros of desalination outweigh the cons? Why or why not?

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Image Attributions

  1. [1]^ Credit: Nina Matthews Photography; Source: http://www.flickr.com/photos/21560098@N06/7525248148; License: CC BY-NC 3.0
  2. [2]^ Credit: eutrophication&hypoxia; Source: https://www.flickr.com/photos/48722974@N07/4538714228; License: CC BY-NC 3.0

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