Chapter 9 Rates of Chemical Reactions | Kentucky State University

University:
Kentucky State University
Course:
CHE 101 | General Chemistry I
Academic year:

2021
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28

Pages:

1
Author:

Cyncuncewc3b4

Chapter 9: Rates of Chemical Reactions FACTORS AFFECTING REACTION RATES 1. The nature of the reactants. - In chemical reactions, some bonds break and others form. - Therefore, the rates of chemical reactions are affected by the nature of the bonds in the reacting substances. 2. The surface area exposed. - Since most reactions depend on the reactants coming into contact, the surface exposed proportionally affects the rate of the reaction. 3. The concentration. - The reaction rate is usually proportional to the concentrations of the reactants. - If more molecules or ions of the reactant are in the reaction area, then there is a greater chance that more reactions will occur. 4. The temperature. - A temperature increase of 10∘ 𝐶above room temperature usually causes the reaction rate to double or triple. - As temperature increases, the average kinetic energy of the particles involved increases. As a result the particles move faster and have a greater probability of hitting other reactant particles. More energy means more effective collisions, resulting in chemical reactions that form the product. 5. The presence of a catalyst. - Aa catalyst is a substance that increases or decreases the rate of a chemical reactionw/o itself undergoing any permanent chemical change. - The catalyst provides an alternative pathway by which the reaction can proceed and the activation energy is lower. Thus increasing the rate the reaction comes to completion or equilibrium. ACTIVATION ENERGY - A reaction rate may be increased or decreased by affecting the activation energy, the energy needed to cause a reaction to occur. - A catalyst is a substance introduced into a reaction to speed up the reaction by changing the amount of activation energy needed.