Chapter 17. Kinetics Show Jessie A. Key
Reaction kinetics is the study of the rate of chemical reactions, and reaction rates can vary greatly over a large range of time scales. Some reactions can proceed at explosively fast rates like the detonation of fireworks (Figure 17.1 “Fireworks at Night Over River”), while others can occur at a sluggish rate over many years like the rusting of barbed wire exposed to the elements (Figure 17.2 “Rusted Barbed Wire”). Figure 17.1 “Fireworks at Night Over River.” The chemical reaction in fireworks happens at an explosive rate.Figure 17.2 “Rusted Barbed Wire.” The rusting of barbed wire occurs over many years.Collision TheoryTo understand the kinetics of chemical reactions, and the factors that affect kinetics, we should first examine what happens during a reaction on the molecular level. According to the collision theory of reactivity, reactions occur when reactant molecules “effectively collide.” For an “effective collision” to occur, the reactant molecules must be oriented in space correctly to facilitate the breaking and forming of bonds and the rearrangement of atoms that result in the formation of product molecules (see Figure 17.3 “Collision Visualizations”). Figure 17.3 “Collision Visualizations.” This visualization shows an ineffective and effective collision based on molecular orientation.During a molecular collision, molecules must also possess a minimum amount of kinetic energy for an effective collision to occur. This energy varies for each reaction, and is known as the activation energy (Ea) (Figure 17.4 “Potential Energy and Activation Energy”). The rate of reaction therefore depends on the activation energy; a higher activation energy means that fewer molecules will have sufficient energy to undergo an effective collision. Figure 17.4 “Potential Energy and Activation Energy.” This potential energy diagram shows the activation energy of a hypothetical reaction.Factors That Affect RateThere are four main factors that can affect the reaction rate of a chemical reaction:
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What are 5 factors that affect reaction rate?There are five general properties that can affect the rate of a reaction:. The concentration of the reactants. The more concentrated the faster the rate.. Temperature. ... . Physical state of reactants. ... . The presence (and concentration/physical form) of a catalyst (or inhibitor). ... . Light.. What are the 7 factors that affect the rate of reaction?The rate of a chemical reaction is affected by several factors like:. Concentration of reactants.. Pressure.. Temperature.. Catalyst.. Nature of reactants.. Orientation of reacting species.. Surface area.. Intensity of light.. What factors change reaction rates?There are four main factors that can affect the reaction rate of a chemical reaction:. Reactant concentration. Increasing the concentration of one or more reactants will often increase the rate of reaction. ... . Physical state of the reactants and surface area. ... . Temperature. ... . Presence of a catalyst.. |