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Development of a thermal equilibrium in a closed system over time through a heat flow that levels out temperature differences. Two physical systems are in thermal equilibrium if there is no net flow of thermal energy between them when they are connected by a path permeable to heat. Thermal equilibrium obeys the zeroth law of thermodynamics. A ...
An example of this is quasi-static expansion of a mixture of hydrogen and oxygen gas, where the volume of the system changes so slowly that the pressure remains uniform throughout the system at each instant of time during the process. [2] Such an idealized process is a succession of physical equilibrium states, characterized by infinite ...
[2] the process of heat or phonon emission by charge carriers in a solar cell, after a photon that exceeds the semiconductor band gap energy is absorbed. [3] The hypothesis, foundational to most introductory textbooks treating quantum statistical mechanics, [4] assumes that systems go to thermal equilibrium (thermalisation). The process of ...
If it is defined that a thermodynamic system is in thermal equilibrium with itself (i.e., thermal equilibrium is reflexive), then the zeroth law may be stated as follows: If a body C, be in thermal equilibrium with two other bodies, A and B, then A and B are in thermal equilibrium with one another. [8]
To maintain this constant entropy, any exchange of work energy with the environment must therefore be quasi-static in nature in order to ensure that the system remains essentially at equilibrium during the process. [1] The opposite of a thermally isolated system is a thermally open system, which allows the transfer of heat energy and entropy.
In solution chemistry and biochemistry, the Gibbs free energy decrease (∂G/∂ξ, in molar units, denoted cryptically by ΔG) is commonly used as a surrogate for (−T times) the global entropy produced by spontaneous chemical reactions in situations where no work is being done; or at least no "useful" work; i.e., other than perhaps ± P dV.
In chemistry, transition state theory (TST) explains the reaction rates of elementary chemical reactions. The theory assumes a special type of chemical equilibrium (quasi-equilibrium) between reactants and activated transition state complexes. [1] TST is used primarily to understand qualitatively how chemical reactions take place.
From these meanings (which actually apply in specific conditions, e.g. constant pressure, temperature, etc.), for positive changes (e.g., ΔU > 0), we can say that ΔU is the energy added to the system, ΔF is the total work done on it, ΔG is the non-mechanical work done on it, and ΔH is the sum of non-mechanical work done on the system and ...