Chemistry

Basic concepts of chemical bonding

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Fuel Cells Chemistry plays a vital role in the production of energy. Today, various chemical reactions are used as alternatives for fossil fuels in the generation of energy. This has been prompted by the fact that the use of fossil fuels is exhaustible and results in harmful emissions. The discovery of fuel cells in 1839 by Sir William Groves has contributed to the use of a more environmental friendly device (Sorensen 34). Fuel cells are electrochemical devices that generate energy through chemical reactions. They utilize elementary oxygen and hydrogen to generate energy. Unlike other energy sources, no combustion is involved. This means that carbon dioxide, nitrous oxide and other harmful gases are not produced. The chemical reactions generate heat and water. The water generated can be employed for other purposes (Renewable Energy World [REW]). This paper will focus on discussing the chemical components of the fuel cells. The fuel cell comprises a cathode, anode and electrolyte. It is also composed of an anode and cathode catalyst layer. The electrode is made up of a porous material. This material has high electron conductivity and zero proton conduction (Robert 684). Porous graphite thin layers have been used as electrodes in various fuel cells. The anode and cathode catalyst layers depend on the type of the fuel cell. Majority of the low temperature fuel cell utilize platinum while nickel is used in the high temperature cells. The electrolyte is a material that transfers ions. In a fuel cell, it is made up of materials that facilitate high proton conduction and theoretically zero conduction of electrons (Rob 10). The charge carriers between the anode and the cathode are made of different materials depending on the fuel cell type. This enables the conveying of electrons from the negatively charged anode to the positively charged cathode. This transfer of electrons facilitates the transfer of energy to an external pathway. The overall chemical reaction in the prototype fuel cell is 2H2+ O2 &gt. 2H2O. In order for the reaction to occur in the fuel cell, hydrogen and oxygen must react in order to generate electrons and form bonds (Larminine 43). At the anode electrode, hydrogen is dissociated into electrons and protons. The chemical reaction at the anode is 2H2 &gt. 4H+ + 4e- where hydrogen is oxidized to release four electrons. These electrons are transmitted through an external pathway to the cathode. They can be used to generate energy thus drive an external device. At the cathode, oxygen is reduced, and dissociates to form water. The electrons that are transmitted through the external pathway and the protons which are transmitted through the electrode react at the cathode. This oxygen proton and electron reaction forms water. The chemical reaction at the cathode is 4H++ 4e- + O2&gt.2H2O (Sorensen 55). Hydrogen (the fuel) enters fuel cell and is mixed with air. therefore, oxidation of the fuel. Hydrogen is broken down to electrons and protons. In the example of PAFC (phosphoric acid Fuel Cells) and PEMFC (proton exchange membrane fuel cells), the positive charge ions move via the electrolyte across a voltage so as to generate electric power. The electrons and protons are then recombined with O2 so to generate water. As H2O is removed, more protons are drawn across the electrolyte. This leads to continued reaction. hence, further power production (Rob 20). In solid oxide fuel cells, it is oxygen radicals that move across the electrolyte, and not the protons. In molten carbonate fuel cells, carbon dioxide is used to react with oxygen and electrons, and combine so as to generate carbonate ions. This are then transmitted through the electrolyte. The hydrogen and oxygen used in these reactions is supplied from the air. Hydrogen can also be produced from natural gases, for example, gasoline. The natural gases are subjected to reforming reactions so as to generate hydrogen. Other sources of hydrogen, for example ammonia, require electricity to spilt hydrogen from the chemical formula. An individual fuel cell is capable of generating about 0.7 to 1.0 volts (Larminine 79). Several cells are connected in series. therefore, generating higher voltages. They can be used to generate energy for mobile and stationary devices. Unlike other forms of energy, the fuel cell does not store energy. Fuel cells produce energy from converting a part of energy from the fuel source supplied. The energy created by the fuel cell is dependent on the number of fuel cells in the stack. This implies that the fuel cell efficiency is not governed by the generation capacity of the cell, but rather the chemical conversion of the reactants. Currently, several factories have applied this chemical advantage to generate energy (REW). In conclusion, chemistry has greatly contributed to the generation and supply of energy. The electrochemical reaction in the fuel cell generates products that can be used for other purposes. The amount of voltage generated by the stack of fuel cell depends on the number of cells. They can thus generate energy that can be used for vehicles and other devices. Works Cited Larminine, James. Fuel cell systems explained. London: Routledge, 2003. Print. Renewable Energy World. Hydrogen Energy, 2012. Web. Accessed on 27th March 2012. Robert, Service. "Bringing Fuel Cells Down to Earth."&nbsp.Science, 285.5427 (30 July 1999): 684. Print. Rob, Thring. Fuel Cell for automotive application. New Jersey: Prentice Hall, 2004. Print. Sorensen, Bent. Hydrogen and fuel cells. NY: Elsevier, 2007. Print.

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