Lecture

Reaction Kinetics: Temperature Influence

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In course

CH-160(b): General chemistry

Cet enseignement vise l'acquisition des notions essentielles relatives à la structure de la matière, aux équilibres et à la réactivité chimiques. Le cours et les exercices fournissent la méthodologie permettant de résoudre par le raisonnement et le calcul ...

Description

This lecture covers the influence of temperature on reaction rates, focusing on the Arrhenius equation proposed in 1889 by Svante Arrhenius. It explains how the speed constant 'k' varies significantly with temperature, introducing concepts such as frequency factor, activation energy, and the ideal gas constant. The lecture also delves into the interpretation of activation energy, the collision complex, and the Arrhenius law for elementary reactions. Additionally, it discusses reaction mechanisms, intermediates, and multi-step reactions, emphasizing the role of catalysts in accelerating reactions and lowering activation energy barriers.

Instructor

Samuel Terrettaz

Teaching & PhD Courses Advanced general chemistry CH-160(f) This course aims at the acquisition of essential notions on the structure of matter, chemical equilibria and reactivity. Theoretical teaching and exercise provide the methodology to analyze and solve by reasoning and calculation novel problems of general chemistry. Advanced general chemistry CH-160(g) This course aims at the acquisition of essential notions on the structure of matter, chemical equilibria and reactivi

Official source

Ontological neighbourhood

Chemistry

Physical chemistry: Chemical kinetics

Related concepts (27)

Chemical reaction

A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei (no change to the elements present), and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes can occur.

Reaction intermediate

In chemistry, a reaction intermediate or an intermediate is a molecular entity that is formed from the reactants (or preceding intermediates) but is consumed in further reactions in stepwise chemical reactions that contain multiple elementary steps. Intermediates are the reaction product of one elementary step, but do not appear in the chemical equation for an overall chemical equation. For example, consider this hypothetical stepwise reaction: A + B -> C + D The reaction includes two elementary steps: A + B -> X X -> C + D In this example, X is a reaction intermediate.

Elementary reaction

An elementary reaction is a chemical reaction in which one or more chemical species react directly to form products in a single reaction step and with a single transition state. In practice, a reaction is assumed to be elementary if no reaction intermediates have been detected or need to be postulated to describe the reaction on a molecular scale. An apparently elementary reaction may be in fact a stepwise reaction, i.e. a complicated sequence of chemical reactions, with reaction intermediates of variable lifetimes.

Enzyme kinetics

Enzyme kinetics is the study of the rates of enzyme-catalysed chemical reactions. In enzyme kinetics, the reaction rate is measured and the effects of varying the conditions of the reaction are investigated. Studying an enzyme's kinetics in this way can reveal the catalytic mechanism of this enzyme, its role in metabolism, how its activity is controlled, and how a drug or a modifier (inhibitor or activator) might affect the rate. An enzyme (E) is typically a protein molecule that promotes a reaction of another molecule, its substrate (S).

Reaction rate

The reaction rate or rate of reaction is the speed at which a chemical reaction takes place, defined as proportional to the increase in the concentration of a product per unit time and to the decrease in the concentration of a reactant per unit time. Reaction rates can vary dramatically. For example, the oxidative rusting of iron under Earth's atmosphere is a slow reaction that can take many years, but the combustion of cellulose in a fire is a reaction that takes place in fractions of a second.

Related lectures (64)

Chemical Kinetics: Elementary Reactions and Reaction Rates

Explores chemical kinetics, reaction rates, reaction orders, rate constants, and enzymatic catalysis.

Chemical Kinetics: Reaction Rates

Explores chemical kinetics, reaction rates, speed laws, and activation energy in various reactions.

Reaction Kinetics: Temperature Influence

Discusses temperature's impact on reaction rates, activation energy, collision efficiency, reaction mechanisms, catalysis, and enzymatic catalysis.