Kinetics Flashcards

Kinetics

A-Level AQA Chemistry

This pack of flashcards covers key concepts of reaction kinetics and collision theory, including definitions of activation energy, the Maxwell-Boltzmann distribution, factors affecting reaction rates like temperature, concentration, surface area, and the role of catalysts. It explains how these factors influence the energy of particles, collision frequency, and effective collisions, contributing to the rate of chemical reactions.

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Describe the collision theory.	Reactions can only occur when collisions take place between particles having sufficient energy.
Define activation energy.	The minimum energy which particles need to collide to start a reaction.
What does the Maxwell-Boltzmann energy distribution show?	The spread of energies that molecules of a gas or liquid have at a particular temperature.
How can a reaction go to completion if few particles have energy greater than EA?	Particles can gain energy through collisions.
What happens to the energy distribution as temperature increases?	The distribution shifts towards having more molecules with higher energies.
What happens to the Emp and mean energy as temperature increases?	Both the Emp and mean energy shift to higher energy values.
What happens to the number of molecules with higher energies as temperature decreases?	The number of molecules with higher energies decreases.
What happens to the energy distribution at higher temperatures compared to lower temperatures?	At higher temperatures, the molecules have a wider range of energies than at lower temperatures.
What is the rate of reaction defined as?	The rate of reaction is defined as the change in concentration of a substance in unit time.
How is the rate of reaction usually measured?	The rate of reaction is usually measured in mol.
Describe how the rate of reaction can be determined from a graph.	The rate of reaction can be determined from a graph by calculating the gradient of the curve.
What is the initial rate of reaction?	The initial rate of reaction is the rate at the start of the reaction where it is fastest.
How can reaction rates be calculated from concentration graphs?	Reaction rates can be calculated from concentration graphs by drawing tangents to the curve at different times and calculating the gradient of the tangent.
What is the effect of increasing concentration on collision frequency?	Increasing concentration leads to a higher frequency of effective collisions due to more particles per unit volume.
What happens to the shape of energy distribution curves when concentration increases?	The shape of energy distribution curves does not change when concentration increases.
What is the relationship between concentration and the area under energy distribution curves?	The area under energy distribution curves increases with higher concentration because there are more particles.
What determines the rate of reaction?	The rate of reaction is determined by factors such as concentration, temperature, and surface area.
Describe the effect of increasing temperature on the rate of a reaction.	At higher temperatures, the energy of the particles increases, resulting in more frequent collisions with energy greater than the activation energy, leading to an increase in the rate of the reaction.
What is the effect of increasing surface area on the rate of a reaction?	Increasing surface area causes successful collisions to occur more frequently between the reactant particles, resulting in an increase in the rate of the reaction.
Define catalysts.	Catalysts are substances that increase reaction rates without getting used up.
How do catalysts increase reaction rates?	Catalysts provide an alternative route or mechanism with a lower activation energy, allowing more particles to have energy greater than the activation energy and increasing the frequency of effective collisions.
Compare the activation energies for an uncatalyzed reaction and the same reaction with a catalyst present.	The activation energy for the reaction with a catalyst present is lower compared to the uncatalyzed reaction.
Describe the progress of a reaction with a lower activation energy.	With a lower activation energy, more particles will have energy greater than the activation energy, resulting in a higher frequency of effective collisions and a faster reaction rate.

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