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Conservation of Mass in Chemical Reactions

Matter cannot be created or destroyed in chemical reactions.

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Where Does All the Carbon Go?

Where Does All the Carbon Go?

Credit: Jim Henderson
Source: http://commons.wikimedia.org/wiki/File:East_River_Station_Av_D_jeh.jpg
License: CC BY-NC 3.0

This oil-burning power plant is located in the middle of New York City. Its smokestacks are equipped with scrubbers. These are devices that remove many of the pollutants from the exhaust gases. But the smokestacks still release gases.

The Back Story

  • Oil is a fossil fuel. Like all fossil fuels-and the living things from which they form-oil consists mostly of carbon. What happens to the carbon in a fossil fuel like oil when it burns? There doesn’t appear to be anything left from the fire. Is the carbon destroyed in the flames?
  • Actually, the carbon still exists because matter can’t be destroyed. Matter is always conserved in chemical reactions. If you don’t believe it, watch this video in which some middle school “scientists” try to demonstrate the law of conservation of matter (or mass): 


What Do You Think?

At the link below, watch a dramatic example of how matter is conserved in the formation and burning of a fossil fuel. Then answer the questions that follow.

  1. What is the law of conservation of mass?
  2. How did the students in the first video demonstrate the law of conservation of mass?
  3. When something burns, it undergoes a combustion reaction. Describe a combustion reaction. How does it follow the law of conservation of mass if there appears to be nothing left after the substance burns?
  4. Identify where the carbon in a fossil fuel goes when it burns.
  5. What do you think? How does the burning of fossil fuels contribute to the greenhouse effect and global warming?

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Image Attributions

  1. [1]^ Credit: Jim Henderson; Source: http://commons.wikimedia.org/wiki/File:East_River_Station_Av_D_jeh.jpg; License: CC BY-NC 3.0

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