Name: arrhenius equation in reaction speed
Uploaded: 2023-04-30T18:28:32.000Z
Duration: 2 min 28 s
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K12 Standards

Louisiana Student Standards for Science

High School

Chemistry

Matter And Its Interactions

HS-PS1-5

effect-of-temperature-change-on-reaction-rate

Effect of Temperature Change on Reaction Rate

La ley de velocidad de una reacción define la relación entre una concentración de reactivo y la velocidad de reacción en términos de una constante de velocidad, 'k'.
La constante de velocidad describe la relación entre la temperatura y los parámetros cinéticos relacionados con la colisión, la orientación y la energía de activación de las moléculas que reaccionan a través de la ecuación de Arrhenius. 'A' es una constante llamada factor de Arrhenius o factor de frecuencia. 'e' es un factor exponencial que integra la energía de activación medida en julios por mol, la constante de gas y la temperatura en kelvin.
La dependencia de la temperatura de los parámetros se puede explicar con el modelo de colisión, que establece que las moléculas que reaccionan deben colisionar con suficiente energía en la orientación correcta para iniciar una reacción química.
El factor de frecuencia constituye dos componentes: la frecuencia de colisión y el factor de orientación. La frecuencia de colisión es el número de colisiones moleculares por unidad de tiempo, mientras que el factor de orientación describe la probabilidad de colisiones con una orientación favorable.
Sin embargo, solo una pequeña fracción de las colisiones conduce a una reacción. Esto se debe a que las moléculas que reaccionan tienen que superar una barrera de energía, llamada energía de activación, para transformarse en productos.
Solo aquellas moléculas que colisionan con suficiente energía cinética tendrán suficiente energía potencial para doblarse, estirarse o romper enlaces para transformarse en un intermediario de alta energía llamado estado de transición o complejo activado. El complejo activado inestable y de vida corta pierde energía para formar productos estables, cuya energía total es menor que la de los reactivos.
El factor exponencial en la ecuación de Arrhenius representa la fracción de colisiones exitosas que resultan en productos. Un aumento de la temperatura influye tanto en el factor de frecuencia como en el factor exponencial.
A temperaturas elevadas, las moléculas se mueven más rápido, con más fuerza y con energías térmicas más altas, lo que lleva a colisiones más favorables.
Para la mayoría de las reacciones, un aumento de temperatura da como resultado una mayor frecuencia y factores exponenciales, lo que lleva a un aumento en la constante de velocidad, lo que se traduce en una velocidad de reacción acelerada.

efecto del cambio de temperatura sobre la velocidad de reacción

La ecuación de Arrhenius,


 <img alt="Figure1" src="/files/ftp_upload/11698/11698_Equation1.svg" style="text-align: center; height: 30px;">


 Relaciona la energía de activación y la constante de velocidad, k, para muchas reacciones químicas.


 En esta ecuación, R es la constante del gas ideal, que tiene un valor de 8,314 J/mol·K, T es la temperatura en grados kelvin, Ea es la energía de activación en julios por mol, e es la constante 2,7183 y A es una constante. llamado factor de frecuencia, que está relacionado con la frecuencia de las colisiones y la orientación de las moléculas que reaccionan.


 El factor de frecuencia, A, refleja qué tan bien las condiciones de reacción favorecen las colisiones correctamente orientadas entre las moléculas reactivas. Una mayor probabilidad de colisiones efectivamente orientadas da como resultado valores mayores para A y velocidades de reacción más rápidas.


 El término exponencial, e−Eₐ/RT, describe el efecto de la energía de activación en la velocidad de reacción. Según la teoría cinética molecular, la temperatura de la materia es una medida de la energía cinética promedio de sus átomos o moléculas constituyentes: una energía de activación más baja da como resultado una fracción más significativa de moléculas adecuadamente energizadas y una reacción más rápida.


 El término exponencial también describe el efecto de la temperatura sobre la velocidad de reacción. Una temperatura más alta representa una fracción correspondientemente mayor de moléculas que poseen suficiente energía (RT) para superar la barrera de activación (Ea). Esto produce un valor más alto para la constante de velocidad y una velocidad de reacción correspondientemente más rápida.


 La energía mínima necesaria para formar un producto durante una colisión entre reactivos se llama energía de activación (Ea). La diferencia entre la energía de activación requerida y la energía cinética proporcionada por las moléculas reactivas en colisión es un factor principal que afecta la velocidad de una reacción química. Si la energía de activación es mucho mayor que la energía cinética promedio de las moléculas, la reacción ocurrirá lentamente, ya que sólo unas pocas moléculas que se mueven rápidamente tendrán suficiente energía para reaccionar. Si la energía de activación es mucho menor que la energía cinética promedio de las moléculas, una gran fracción de moléculas tendrá la energía adecuada y la reacción se desarrollará rápidamente.


 Los diagramas de reacción se utilizan ampliamente en cinética química para ilustrar diversas propiedades de una reacción de interés. Muestra cómo cambia la energía de un sistema químico a medida que sufre una reacción, convirtiendo los reactivos en productos.

Efecto del cambio de temperatura sobre la velocidad de reacción

La ecuación de Arrhenius,

relaciona la energía de activación y la constante de velocidad, k, para muchas reacciones químicas.
En esta ecuación, R es el gas ideal ...

Education

Educación

JoVE Core

Organic Chemistry

Química Orgánica

Unit 1

Unidad 1

Thermodynamics and Chemical Kinetics

Termodinámica y cinética química

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

arrhenius equation in reaction speed

The Arrhenius equation connects activation energy, temperature, and the rate constant, k, for many chemical reactions. It helps explain why some reactions move slowly while others happen faster.

In this equation, R is the ideal gas constant, with a value of 8.314 J/mol·K. T is the temperature in kelvin, Ea is the activation energy in joules per mole, e is the constant 2.7183, and A is the frequency factor.

The frequency factor, A, describes how often reacting molecules collide and how well they are oriented during those collisions. Better orientation increases the chance of effective collisions. That leads to larger A values and faster reaction rates.

The exponential term, e−Ea/RT, shows how activation energy affects the reaction rate. Kinetic molecular theory says that temperature measures the average kinetic energy of atoms or molecules. When activation energy is lower, more molecules have enough energy to react, and the reaction is faster.

The same exponential term also shows the effect of temperature. At higher temperature, a larger fraction of molecules has enough energy, RT, to get over the activation barrier, Ea. This increases the rate constant and speeds up the reaction.

Activation energy is the minimum energy needed to form products during a collision between reactants. If Ea is much larger than the average kinetic energy of the molecules, only a few fast-moving molecules can react, so the reaction is slow. If Ea is much smaller than the average kinetic energy, many molecules can react, so the reaction proceeds quickly.

Reaction diagrams are often used in chemical kinetics to show how a system’s energy changes as reactants turn into products. They help visualize the energy barrier and the path from reactants to products. This text is adapted from Openstax, Chemistry 2e, Section 12.5: Collision Theory.

Arrhenius Equation in Reaction Speed

chemical reactions

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rate law and reaction order

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effect of temperature change on reaction rate

The Arrhenius equation connects activation energy, temperature, and the rate constant, k, for many chemical reactions. It helps explain why some reactions move slowly while others happen faster. In this equation, R is the ideal gas constant, with a value of 8.314 J/mol·K. T is the temperature in kelvin, Ea is the activation energy in joules per mole, e is the constant 2.7183, and A is the frequency factor. The frequency factor, A, describes how often reacting molecules collide and how well...

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Reaction rate and reaction pathway are key ideas in chemical kinetics. Thermodynamics, by contrast, focuses on the state of a system. It describes the properties, behavior, and components of reactants and products. It does not describe the path of the process or the speed of the reaction. Kinetics gives information on the atomic or molecular level, while thermodynamics focuses on the energetics of the reactants and products. Thermodynamics can show what may happen in a reaction, but it does...

key terms and concepts

Explore how the Arrhenius equation links temperature, activation energy, and collision orientation to reaction speed in high school chemistry.

Arrhenius Equation in Reaction Speed | JoVE K12

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JoVE Core Química Orgánica explica los conceptos básicos de la estereoquímica, las reacciones y sus mecanismos mediante lecciones de vídeo animadas, concisas y fáciles de entender. Además, los vídeos de científicos en acción muestran la aplicación de esos conceptos en experimentos de investigación clásicos y originales, desarrollados actualmente en laboratorios de todo el mundo.

Minnesota Academic Standards in Science

9-12

3.2.1 9C.3.1.1.2

Florida Department of Education

Physical Science

SC.912.P.12

SC.912.P.12.12

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HS-PS1-4

Arrhenius Equation in Reaction Speed

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