Chemical Equilibrium. - 港Chem 5**化學補習補chem 化學補習 Hkdse

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Chemical equilibrium is the state of a reaction where the rate of the forward and reverse reactions are equal. This is a dynamic concept, as the reactions are still occurring, but at the same rate. In a chemical reaction, the reactants change into products in a forward reaction, and the products can also change back to reactants in a reverse reaction. The equilibrium point is the point where the concentrations of reactants and products no longer change.

This concept was first proposed by French chemist Claude Louis Berthollet in 1803 and was later developed by Danish physicist Søren Sørensen and Norwegian physical chemist Peter Waage in the 1860s. The three scientists independently discovered the Law of Mass Action that explains the relationship between the concentrations of reactants and products.

The law of mass action states that the rate of a chemical reaction is proportional to the concentrations of the reactants raised to their stoichiometric coefficients. The stoichiometric coefficients refer to the coefficients of a balanced chemical equation.

For example, consider the reaction between nitrogen and hydrogen to form ammonia:

N2(g) + 3H2(g) ⇌ 2NH3(g)

The equilibrium constant for this reaction is given by:

Kc = [NH3]² / [N2][H2]³

where [NH3], [N2], and [H2] are the concentrations of ammonia, nitrogen, and hydrogen respectively.

A high value of Kc indicates that the equilibrium lies towards the right (product side), whereas a low value indicates that the equilibrium lies towards the left (reactant side).

There are several factors that can affect the position of the equilibrium in a chemical reaction. These include changes in temperature, pressure, concentration, and the addition of a catalyst.

Le Chatelier’s principle states that a system at equilibrium will respond to any external stress or disturbance in such a way as to partially offset the stress. For example, if more reactants are added to a reaction at equilibrium, the equilibrium will shift to produce more products until the original equilibrium is re-established.

In industries, chemical equilibrium is an important concept in the optimization of chemical reactions. Knowing the position of the equilibrium and the factors that can affect it, one can adjust the conditions to maximize the yield of the desired product.

In conclusion, chemical equilibrium is an important concept in chemistry and explains the dynamic nature of chemical reactions. Knowing how to manipulate the conditions of a reaction to achieve the desired equilibrium can be useful in optimizing the production of chemicals in industries.
化學平衡是一種反應狀態，其中正反應速率相等。這是一個動態概念，因為反應仍在進行中，但速率相同。在化學反應中，反應物在正向反應中轉變為產物，產物也可以在逆向反應中變回反應物。平衡點是濃度不再改變的點。

這個概念最初由法國化學家Claude Louis Berthollet於1803年提出，後來由丹麥物理學家Søren Sørensen和挪威物理化學家Peter Waage在1860年代進一步發展。這三位科學家獨立發現了質量作用定律，該定律解釋了反應物和產物濃度之間的關係。

質量作用定律指出，化學反應的速率與反應物濃度呈比例關係，指數等於反應物在化學平衡方程式中的化學計量係數。化學計量係數是平衡方程式中平衡反應物與產物的化學計量係數。

例如，考慮氮氣和氫氣形成氨氣的反應：

N2(g) + 3H2(g) ⇌ 2NH3(g)

此反應的平衡常數為：

Kc = [NH3]² / [N2][H2]³

其中[NH3]，[N2]和[H2]分別為氨氣，氮氣和氫氣的濃度。

較高的Kc值表明平衡向右偏（產品側），較低的值則表明平衡向左偏（反應物側）。

化學反應平衡位置的幾個因素，包括溫度，壓力，濃度和催化劑添加等。勒夏特列原理指出，處於化學平衡的系統將對任何外部壓力或干擾作出反應，以部分抵消壓力。例如，如果在反應平衡中添加了更多的反應物，平衡將移動以產生更多產物，直到重新建立原來的平衡。

在工業中，化學平衡是優化化學反應的重要概念。了解平衡的位置和可以影響平衡的因素，可以調整條件以最大化所需產品的產量。

總之，化學平衡是化學中的重要概念，解釋了化學反應的動態特性。知道如何操縱反應的條件以達到所需的平衡，在工業中優化化學產品的生產可以非常有用。