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Chapter 20

The First Law of Thermodynamics

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A thermodynamic system is a set of objects whose thermodynamic properties are of interest. The system is considered to be embedded in its surroundings or …
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In mechanics, work is done on an object when the force acting on it displaces the object. In thermodynamics, work done on a system can be estimated when …
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Consider the two thermodynamic processes involving an ideal gas that are represented by paths AC and ABC in Figure 1: In the first process for path A to …
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The work done by a thermodynamic system depends not only on the initial and final states but also on the intermediate states—that is, on the path. …
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The internal energy of a thermodynamic system is the sum of the kinetic and potential energies of all the molecules or entities in the system. The kinetic …
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A change in the internal energy of a system depends on the the net heat transfer into the system and the net work done by the system. The first law of …
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The first law of thermodynamics states that the change in internal energy of the system is equal to the net heat transfer into the system minus the net …
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A thermodynamic system with zero heat exchange and work is an isolated system. For these systems, the internal energy remains constant. In the case of a …
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A thermodynamic process that occurs at constant temperature is called an isothermal process. Heat slowly flows into the system or out of the system to …
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A thermodynamic process that occurs at constant volume is called an isochoric process. According to the first law of thermodynamics, heat supplied or …
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Heat capacity is the ratio of heat absorbed by the substance corresponding to its temperature change. It is also called thermal capacity and the SI unit …
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For a system that undergoes a thermodynamic process at a constant volume condition, the heat absorbed is used only to increase the system's internal …
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The number of independent ways a gas molecule can move along straight line, rotate, and vibrate is called its degrees of freedom. Supposing d represents …
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When an ideal gas is compressed adiabatically, that is, without adding heat, work is done on it, and its temperature increases. In an adiabatic expansion, …
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Free expansion of a gas is an adiabatic process. However, there are few differences between free expansion and adiabatic expansion. During free expansion, …
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Consider the adiabatic compression of an ideal gas in the cylinder of an automobile diesel engine. The gasoline vapor is injected into the cylinder of an …
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Thermodynamic potentials are state functions that are extremely useful in analyzing a thermodynamic system. They have dimensions of energy. The four …
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Maxwell's thermodynamic relations are very useful in solving problems in thermodynamics. Each of Maxwell's relations relates a partial …
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The Joule-Thomson effect, also known as the Joule-Kelvin effect, describes the temperature change of a fluid when it is forced through a valve or porous …
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Photothermal beam deflection together with photo-acoustic calorimetry and thermal grating belongs to the family of photothermal methods that monitor the …
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Biofilms can cause serious concerns in many applications. Not only can they cause economic losses, but they can also present a public health hazard. …
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Differential scanning calorimetry (DSC) is an analytical technique that measures the molar heat capacity of samples as a function of temperature. In the …
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Low-grade heat is abundantly available in the environment as waste heat. The efficient conversion of low-grade heat into electricity is very difficult. We …