Tổng quan nhiệt động học phản ứng


Nhiệt động học được xem xét trên khía cạnh năng lượng lưu trữ trong 1 phản ứng, 1 chất tham gia hay 1 sản phẩm. Là sự khác biệt năng lương tự do giữa chất tham gia và sản phẩm.

Thermodynamics can be considered in terms of the energy stored within a reaction, a reactant, or a product. Most often, thermodynamics is thought of as the different forms of energy that are converted every time a reaction emits energy or is initiated by energy. With respect toGibbs free energy (ΔG), thermodynamics refers to either (1) the energy released during a reaction, in which case ΔG will be negative and the reaction exergonic or spontaneous, or (2) the energy consumed during a reaction, in which case ΔG will be positive and the reaction endergonic or nonspontaneous. A thermodynamic reaction favors the products, resulting in a spontaneous reaction that occurs without the need to constantly supply energy. This indicates that the reactions’ most stable state is that of the products.

Thus, going back to Diagram #1, thermodynamics is what describes the free energy between the reactants and the products. Because thermodynamic values apply only after the reactants have turned into products, they are said to describe the equilibrium state. The relationship between free energy (aka, Gibbs free energy) and other thermodynamic quantities is expressed mathematically in the following equation:

G=U+pVTS

Because “U” is the variable representing the internal energy of a system, it is closely correlated with the free energy. Changes in internal energy change the value of the free energy, in turn affecting chemical reactions in several ways: the rate of reaction, whether the reaction is spontaneous or non-spontaneous, and even whether or not activation energy will be needed to initiate the reaction.

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