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Date: 19-7-2017
152
Date: 25-9-2018
139
Date: 19-7-2017
152
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Elementary Reactions
A reaction mechanism consists of a series of elementary reaction steps, the sum of which is the stoichiometric chemical equation. An elementary reaction is a precise statement of the molecules which react or are formed in a single step of a mechanism. When we write a mechanism with its elementary reaction steps, we are forming a hypothesis that we hope to test with experimental rate data. The first step in such a test is to derive the rate law expected from the postulated mechanism.
The molecularity specifies the number of molecules involved as reactants in an elementary step. A unimolecular reaction is a step in which a single A molecule undergoes a reaction; the rate of such a step is first-order, k1[A]. A bimolecular reaction is a step in which two molecules react, A + B or 2 A; the rate of such a step is first-order in each reacting species, k2[A][B] or k2[A]2. A termolecular reaction is a step in which three molecules react, A + B + C or 2 A + B or 3 A; the rate of such a step is first-order in each reacting species and third-order overall.
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"عادة ليلية" قد تكون المفتاح للوقاية من الخرف
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ممتص الصدمات: طريقة عمله وأهميته وأبرز علامات تلفه
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الأمين العام للعتبة العسكرية المقدسة يستقبل معتمد المرجعية الدينية العليا وعدد من طلبة العلم والوجهاء وشيوخ العشائر في قضاء التاجي
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