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pH scale

Defines the pH scale and shows the pH of many common solutions.

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Dissolving Teeth

Dissolving Teeth


Credit: Biser Todorov
Source: http://commons.wikimedia.org/wiki/File:Rusty_tools.JPG
License: CC BY-NC 3.0

Rust is one of those problems that we can find anywhere. Rusty tools need to be cleaned so they can be used again. Folklore (supported by information on the internet) tells us we can remove rust from metals by soaking the object in a soft drink. The active ingredient in the process is the phosphoric acid in the drink. This acid converts the ferric oxide to ferric phosphate that can be washed off, restoring the metal to its original state.

News You Can Use

  • In 2012, soft drink sales amounted to two sodas/day for each individual in the country. These highly sugared drinks also contain a significant amount of acid in them. Dissolved carbon dioxide accounts for part of the acidity, while phosphoric acid or citric acid makes up the major portion of the hydrogen ions present in the drink.
  • The pH of a solution is an indication of the hydrogen ion concentration. Many soft drinks have very acidic pH values, often being well below pH 3. The cola drinks seem to have the lowest pH values. In contrast, the pH of bottled water (non-carbonated with no additives) is about pH 7.
  • There is growing concern about the health and dietary impact of soft drinks. Increasingly, schools are no longer allowing these items to be sold on campus and parents are being encouraged to limit their children’s consumption of soft drinks. One major health issue deals with the high amount of sugar contained in the beverages. Many consumers are moving to diet drinks (which contain artificial sweeteners) or bottled water.
  • Credit: U.S. Department of Agriculture
    Source: http://www.flickr.com/photos/usdagov/9458110879/
    License: CC BY-NC 3.0

    Childhood obesity is now carefully monitored [Figure2]

  • Watch a video describing the effects of soft drinks on teeth: https://www.youtube.com/watch?v=OXOcTTyYiR4

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Use the links below to learn more about acidity in drinks. Then answer the following questions.

  1. Do cola drinks have higher or lower pH values than non-cola ones?
  2. How much carbon dioxide was found in the soft drink bottle?
  3. Who first developed a process for artificially carbonating drinks?
  4. Why is phosphoric acid added to drinks?
  5. How do soft drinks affect tooth enamel?

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Image Attributions

  1. [1]^ Credit: Biser Todorov; Source: http://commons.wikimedia.org/wiki/File:Rusty_tools.JPG; License: CC BY-NC 3.0
  2. [2]^ Credit: U.S. Department of Agriculture; Source: http://www.flickr.com/photos/usdagov/9458110879/; License: CC BY-NC 3.0

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