Fuels as Sources of Energy

EXAMPLE 7-13 Calculating the Enthalpy Change in an Ionic Reaction 

Given that AfH°[BaS04(s)] = —1473 kj/mol, what is the standard enthalpy change for the precipitation of barium sulfate  

write the net ionic equation for the reaction and introduce the relevant data. Then make use of equation (7.22). 

The standard enthalpy of reaction determined here is the heat given off by the system (i.e., the ionic reaction). 

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Rnally, we examine foods and fuels as sources of energy and discuss some related health and social issues. 

Plaster of Paris is produced by a dry dehydration (calcination) of calcium sulfate dihydrate, which is available either as natural gypsum or as a by-product of the chemical industry. Increasing amounts of dihydrate are also produced as flue gas gypsum in the desulfurization of flue gas in power plants that use sulfur-containing fossil fuels as source of energy. A number of technologies are available to produce plaster of Paris. 

Fuels as Sources of Energy—One of the chief applications of thermochemistry is in the study of the combustion of fuels as energy sources. Currently, the principal fuels are the fossil fuels, but potential alternative fuels are also mentioned in this chapter and discussed in more depth later in the text. One of the problems with the use of fossil fuels is the potential for global warming. 

It is useful to examine the combustion process appHed to soHd wastes as fuels and sources of energy. AH soHd wastes are quite variable in composition, moisture content, and heating value. Consequendy, they typically are burned in systems such as grate-fired furnaces or duidized-bed boilers where significant fuel variabiUty can be tolerated. 

About eight gallons of coal tar are obtained from a ton of coal. Coal tars are very complex mixtures over 200 different carbon compounds have been isolated from them. While the great value of coal to mankind has been as a fuel, a source of energy, the many substances in coal gas and coal tar make coal also an important source of chemical raw materials. 

The major site of the production of acetoacetate and 3-hydroxybutyrate is the liver. These substances diffuse from the liver mitochondria into the blood and are transported to peripheral tissues (Figure 22,21). Acetoacetate and 3-hydroxybutyrate are normal fuels of respiration and are quantitatively important as sources of energy. Indeed, heart muscle and the renal cortex use acetoacetate in preference to glucose. In contrast, glucose is the major fuel for the brain and red blood cells in well-nourished people on a... 

Compare nuclear fission and nuclear fusion as sources of energy. Name the fuels, benefits, problems, and current status. 

Sason My plan is to teach a mixture of things, both practical and creative. Molecules, especially those made from C and H, are very practical and serve as sources of energy. We shall learn what happens when fuel bums. 

Annually renewable natural products have always been major sources of polymers for industrial applications. Today, the world s most used non-food polymer is cellulose in fiber, film, paper, and housing applications. Starch and protein are useful both as food and feed products as well as industrial products. Natural products have been sources of chemicals by extraction of them from the products. Modification of these products through the actions of microorganisms and destructive distillation also yield industrial chemicals. With the development of internal combustion engines early in this century, natural products were proposed as sources of energy, particularly as a source of liquid motor fuels. 

The second advantage of direct conversion of chemical to electrical energy— the absence of air pollution—make fuel-cells very attractive. While fuel cells do have some wastes, it is reasonable to hope that these wastes can be dealt with more easily than can air pollution. However, available devices use rather expensive materials as sources of energy and one always wanted to use cheap materials, such as gas, oil or coal and atmospheric oxygen for the construction of energy producing devices. 

Solar energy can also be used to cook food. Solar cookers, which do not require the use of fuel, are built and available in the shape of solar panel cookers, hotpots, and solar kettles. Since solar cooking works effectively in remote locations, it can reduce problems associated with deforestation and desertification in developing countries that rely heavily on wood and biomass as sources of energy for cooking. 

The same method could also be applied to the net substrate oxidation rates. Due to the - at least partial - mutual exchangeability of the substrates as source of energy, this approach was not fully functional for the substrates. In [29] a diet containing 37 % of protein, 4 % of fat and 51 % of CHO (The remainder consists of dietary fiber, water, minerals, etc.) was used. In this case by increasing the protein intake by 1 g the CHO intake was automatically increased by 1.4 g. And in energy metabolism CHO is preferred, as long as there is enough CHO from both intake and body stores available. So the relation of the substrates as fuel differed at different levels of diet intake. This resulted in a fat utilisation factor of up to 800 % and CHO utilisation factors of as low as 33 %. The CD s, however, remained at levels of 92 - 99 %. Only for carbohydrate and... 

What is the major source of irreversibility in a steam power plant using a fossil fuel as source of thermal energy ... 

Thorium, uranium, and plutonium are well known for their role as the basic fuels (or sources of fuel) for the release of nuclear energy (5). The importance of the remainder of the actinide group Hes at present, for the most part, in the realm of pure research, but a number of practical appHcations are also known (6). The actinides present a storage-life problem in nuclear waste disposal and consideration is being given to separation methods for their recovery prior to disposal (see Waste treati nt, hazardous waste Nuclear reactors, waste managet nt). 

Fuel. Natural gas is used as a primary fuel and source of heat energy throughout the iadustrialized countries for a broad range of residential, commercial, and iadustrial appHcations. The methane and other hydrocarbons react readily with oxygen to release heat by forming carbon dioxide and water through a series of kinetic steps that results ia the overall reaction,... 

Fuels ndEfficiency. Natural gas, oil, and electricity are the primary sources of energy propane is used as backup reserve in emergencies. Natural gas is the least expensive and most frequently used fuel, with heat content ranging from 34—45 MJ/nf (900—1200 Btu/ft ) for raw gas and approximately 3 MJ/m (80 Btu/fT) for air-gas mixtures. Fuel oil has heat content between 39—43 MJ/L (139,600—153,000 Btu/U.S. gal). Fuel oil is viscous at low temperature and must be heated before being fed to atomizing burners where it is mixed with air for combustion. 

Combustion. The burning of soHd, Hquid, and gaseous fuels as a source of energy is very common. Using sufficient and reHable combustion controls, this process seldom causes serious problems. However, some combustion processes are deHberately carried out with an inadequate oxygen supply in order to obtain products of incomplete combustion. Explosive mixtures sometimes occur, and then flashback is a serious problem. 

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