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Free Energy

Defines free energy and how entropy and enthalpy affect its value.

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Burger Time

Burger Time

Credit: Justin Connaher
Source: https://upload.wikimedia.org/wikipedia/commons/thumb/1/10/From_left%2C_U.S._Army_Staff_Sgt._Bennett_Chandler%2C_with_the_98th_Maintenance_Company%3B_Pfc._Willie_Craft%2C_with_the_40th_Quartermaster_Detachment%3B_and_Pvt._Chric_Munoz%2C_with_the_545th_Military_Police_Company%3B_grill_120810-F-LX370-340.jpg/1280px-thumbnail.jpg
License: CC BY-NC 3.0

The grill is loaded with charcoal, which is then soaked with lighter fluid and ignited. It takes a while for those briquettes to be ready, glowing warmly. Then the burgers are placed in the grill and carefully watched. At just the right time, they are flipped to cook the other side. Finally the call goes out: “Who’s hungry?” And the scramble for charcoal-broiled burgers begins.

News You Can Use

  • Charcoal is a material used in many parts of the world for heating and cooking. This material is prepared by heating wood in the absence of oxygen for several days. Traditional methods involved stacking wood and then covering it with dirt before starting the fire. Modern production usually employs large concreteor steel containers, burning off water, methane, and tars.
  • Credit: TREEAID
    Source: http://www.flickr.com/photos/53871588@N05/6115125029/
    License: CC BY-NC 3.0

    Due to the lack of access to electricity and natural gas, charcoal is the main source of heat for cooking in many third world countries. This poses an envrionmental problem because the charcoal is made from wood which is not harvested in a sustainable fashion, leading to deforestation in these countries [Figure2]

  • Once ignited, combustion of charcoal is a spontaneous reaction, producing carbon dioxide and water as products. Burning charcoal will produce a large amount of energy. Heat production from charcoal is almost double that obtained from burning raw wood. There is little smoke associated with burning charcoal (unless the grease dripping from the burger catches on fire), but this fuel produces much more ash.
  • Activated charcoal has a number of internal pores that can be useful for many purposes. In the laboratory, this form of charcoal is often used to purify a compound by absorbing contaminants. Certain medical treatments employ activated charcoal to trap toxic materials in the stomach so they are not absorbed into the blood stream. On occasion, this material might be used to trap bile acids in the intestine as an approach to lowering cholesterol or in dealing with gall bladder problems.
  • Watch a video about a traditional methods of making charcoal at the link below:


Show What You Know

Use the links below to learn more about charcoal. Then answer the following questions.

  1. What is the char mixed with before being pressed into the final product?
  2. How is activated charcoal prepared?
  3. Compare the volatile matter in charcoal with that in raw wood.
  4. What is one environmental concern with using charcoal?

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