Gummy Bear Experiment

Combustion of Gummy Bears Energy is a concept.? Most definitions of the word energy fail to provide its exact meaning when applied to scientific matters.? In science the word energy is a concept that expresses two measurable properties, heat and work.? Here is the relationship of energy, heat and work: Energy Released=Work Done + Heat Released The Law of Conservation of Energy, derived from centuries of observation and measurement, indicates that energy cannot be created or destroyed. But energy need not stay in one place. Energy can be converted from one form to another and can be created in one place and show up in another. Remember that energy, in an open system, can do work on the surroundings or supply heat to the surroundings.? When we express energy as the sum of heat and work, we are making a very specific claim concerning these two properties. They are related. The relationship between heat and work is a close one, so close the amount of heat and the amount of work must be expressed with numerical values having the same units. Within limits, energy may be controlled to appear as heat (as we use electric power to dry clothes in a dryer) or work (the same electric power rotating the drum in the same dryer). Briefly, we define the amount of heat and/or work using two units, the Joule (J), and the calorie. The Joule and the calorie are related as follows: 1 cal = 4. 184J Both units represent quite small increments of energy. We must add 1 calorie of heat to increase the temperature of 1g of water 1 degree Celsius. Our bodies expend about 1J of work with a single heartbeat. For convenience sake, both the Joule and calorie are often expressed in multiples of 1000. We speak of the kilojoule (kj): 1 kJ = 1000J and the kilocalorie (kcal). 1 kcal = 1000 cal Thus we must add 4. 184 kJ of heat to raise the temperature of 100g of water 10 degrees Celsius. Chemical Reactions and the Production of Energy Heat and Work We learned the foundation of thermochemistry rests on the ability to link the amount of energy released or required to the chemical equation for the specific chemical change. We often experiment under conditions where no work is done on or by the system.? The heat, evolved or required is the change in enthalpy. We use the change in enthalpy of the fuel-consuming chemical reactions to arrive at the energy that would be available. The amount of energy available from a given amount of fuel does not vary with how slow or fast we burn the fuel such as in exercise. Enthalpy itself is a state property. All materials have enthalpy as an element of their nature. It is the change in this property through chemical processes which concerns us. The oxidation of 0. 5g of glucose yields a certain amount of energy regardless of how slow or fast the reaction takes place.? In the real world (during exercise for example), energy, work and heat, are produced in complex, changing systems. The combustion of a gummy bear shows how a compound is broken down into an element and other compounds in the presence of a catalyst or heat. An organic carbon compound will combine with oxygen to give off carbon dioxide and water. An exothermic reaction releases different forms of energy. Sugar is a fuel that we use for energy. We can also use it to fuel a chemical reaction. As we heat the Potassium Chlorate this will release O2 gas and leave KCl as it starts to decompose as follows: 2KClO3(s) ? 2KCl(s) + 3O2 (g) This produces oxygen which oxidizes the sugar (glucose) in the gummy bear. This oxidation is incredibly exothermic (-5000 kJmol-1). The reaction is: C6H12O6(s) + 6O2 (g) ? 6CO2 (g) + 6H2O (g) All chemical reactions involve a change in substances and a change in energy. Neither matter nor energy is created or destroyed in a chemical reaction only changed. This experiment is a decomposition reaction a more complex substance breaks down into its more simple parts. One reactant yields 2 or more products. The presence of oxygen in the decomposition reaction is seen when heat energy is added to potassium chlorate, and its decomposition releases O2 and leaves KCl, when bubbles form. Heat is necessary in this reaction because the excess of oxygen, generated by the decomposition of potassium chlorate, will react with the glucose in a gummy bear, releasing a large amount of energy quickly and dramatically. When it comes in contact with the oxygen in the test tube some of the sucrose disintegrates and this releases heat energy. The released heat causes the potassium chlorate to release more oxygen and a positive feedback loop develops. The difference between endothermic and exothermic reactions is that endothermic reactions absorb heat, and exothermic give off heat. Dilution of ammonium chloride is an example of an endothermic reaction. This is the active ingredient in chemical ice packs you can obtain in a pharmacy. Other reactions are melting and boiling which also absorb heat to happen, although you may not consider them chemical reactions. Combustion is a typical exothermic reaction any type of burning. An exothermic reaction occurs if the energy of the bonds formed in the products are stronger (lower energy) than the bonds broken in the reactants. Endothermic reactions require heat. If there is no external source, the reaction gets the heat by cooling to a lower temperature. These reactions are driven by the change in the configuration of the atoms. If the atoms in the product molecules have a less orderly structure than the atoms in the reactants, these reactions will occur even if the cost some energy to happen. Potassium Chlorate is the oxidizing agent and when it is melted; its decomposition provides an oxygen rich environment. A gummy bear is dropped into the liquid and immediately begins to combust. The heated mixture ignites and oxidizes the sugar in the gummy bear in a violent, exothermic reaction. The gummy bear explodes because the combination of one gummy bear which is composed mostly of sucrose with molten potassium chlorate the gummy bear explodes. A surprising amount of energy is released by the reactants and in the process their atoms and molecules rapidly rearrange to form the products carbon dioxide, water and potassium chloride. The products of the reaction are H2O (vapor) and CO2. Ideally, a balanced equation would show sucrose (C12H22O11) being converted to carbon dioxide and water while the KClO3 becomes KCl. But the combustion was incomplete and carbon and or carbon monoxide were additional products. Bibliography † Endo, Exothermic Reactions and Energy. † Ask a scientist, Newton. 4 Jun 2002, Chemistry Archive, Inc. . Dr. Matt Hermes â€Å"Gatorade. † Chemical Reactions, General Chemistry Case Studies. 14 Jun 2002, Inc . â€Å"Chemistry problems. † Chemistry, The Scientific Forum. 8 Mar 2003 . R Gallagher â€Å"Chemistry Made Clear. † GCSE edition. 6 Dec 1997. .