lecture3 - Chemical systems and energy Learning goals...

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Chemical systems and energy
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Learning goals ± Distinguish between kinetic and potential energy. ± Calculate the enthalpy change for any rection. ± Drawing of potential energy diagrams. ± Calculate the heat of combustion of a substance. ± Convert heat of reaction from a mole to a gram basis. ± How different food values differ in fuel value.
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Energy ± Our focus in this chapter is on energy, and its involvement in chemical processes. Most energy produced in modern societies come from chemical reactions. ± What is energy? ± We cannot see, touch, or smell energy as we do with matter. Therefore to define energy ± Energy is the capacity to do work, or to transfer heat. ± In thermodynamics, the internal energy is the total energy contained by a thermodynamic system , Internal energy has two major components, kinetic energy and potential energy.
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work ± Work is defined and measured by the product of the net force (f) and the distance (d) through which that force moves. ± w = d ± Work is the movement of an object against some force and energy is the something that is required to perform work. ± Matter is the substance of the universe and energy is the mover of the substance.
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Law of conservation of energy (first law of thermodynamics) ± Energy is subject to the law of conservation of energy. According to this law: ± Energy can neither be created (produced) nor destroyed by itself. It can only be transformed. ± According to the law of conservation of energy: Total inflow of energy into a system must equal the total outflow of
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Forms of energy ± Energy found in a variety of forms such as heat energy (thermal), light (radiant), chemical energy , mechanical energy, and electrical energy. ± The various forms or types of energy can be classified as either Kinetic Energy = it is the energy of motion Potential energy = it is the energy stored in an object by virtue of its position or equilibrium.
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Kinetic Energy(Energy of motion) ± The kinetic energy is due to the motion of the system's particles (translations, rotations, vibrations ± The magnitude of K.E. of an object depends on its mass (m) and velocity (v). ± Ek=1/2 mv2. ± The larger the mass of a moving object and the greater its velocity, the more work it can do. ± The SI unit of energy is the joule (J). ± A joule is 1 kg m2/sec2.
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Distinction between energy and power ± In everyday usage the terms energy and power are synonyms, scientists and engineers distinguish between them. ± Power
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lecture3 - Chemical systems and energy Learning goals...

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