Скачать или смотреть Kinetics | Reaction Mechanisms and Multi-step reactions | A level H2 Chem | Making Sense Chem

A LEVEL CHEMISTRY!!
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Zight - Paradise - https://thmatc.co/?l=3B73F710
In today's video, we will be re-visiting at the most important concepts in the chapter Kinetics!

0:00 Introduction
0:55 Reaction mechanisms involving multiple steps
6:45 Energy profile diagrams
10:35 Elementary reactions

Reaction mechanisms involving multiple steps
• Identify intermediates and catalysts in the overall equations.
Catalysts are first consumed, then regenerated.
Intermediates are generated, then consumed.
• Intermediates DO NOT appear in overall eqn
• Order of the reagents corresponds to the stoichiometry of the reagents in the SLOW STEP.
• If there are intermediates in the rate equation, remove the intermediates by writing an equilibrium constant for the reversible reaction involving the intermediate.
• Make the intermediate the subject of the Kc expression and substitute it into the rate equation.

Energy profile diagrams
• Always draw in the axes first. Y axis: energy; X axis: progress of reaction
• The number of “humps” on the graph corresponds to the number of steps in the reaction.
• The slowest step has the highest activation energy hence has the largest hump on the energy diagram.
• Activation energy is labelled from the energy of reactants to pointing to the highest energy point.
• The highest activation energy corresponds to the slow step of the reaction.
• All intermediates are to be included in the energy profile diagram.

Elementary reactions
• Since there is only one step in the reaction, that step is the slow step.
• The stoichiometry of the reagents in elementary reaction is therefore the order of the reagents.
• Only for elementary reactions, the order of reaction corresponds to the stoichiometry in overall equation.

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