General, Organic, & Biological Chemistry Chapter 9 PDF

Chapter 9 Chemical Reactions  Section 9.2 Redox and Nonredox Reactions We do not cover redox number calculations. Section 9.2...

Chapter 9 Chemical Reactions  Section 9.2 Redox and Nonredox Reactions We do not cover redox number calculations. Section 9.2 Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 2  Chapter 9 Chapter Outline 9.1 Types of chemical reactions 9.2 Redox and nonredox chemical reactions 9.3 Terminology associated with redox processes 9.4 Collision theory and chemical reactions 9.5 Exothermic and endothermic chemical reactions 9.6Factors that influence chemical reaction rates 9.7 Chemical equilibrium 9.8 Equilibrium constants 9.9 Altering equilibrium conditions: Le Châtelier’s principle Copyright ©2016 Cengage Learning. All Rights Reserved. 3  Section 9.1 Types of Chemical Reactions Chemical Reaction Process in which at least one new substance is produced as a result of chemical change Major types of chemical reactions: – Combination – Decomposition – Displacement – Exchange – Combustion Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 4  Section 9.1 Types of Chemical Reactions Combination Reaction Chemical reaction in which a single product is produced from two (or more) reactants X + Y → XY Ca + S → CaS Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 5  Section 9.1 Types of Chemical Reactions Decomposition Reaction Chemical reaction in which a single reactant is converted into two (or more) simpler substances (elements or compounds) XY → X + Y 2CuO → 2Cu + O2 Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 6  Section 9.1 Types of Chemical Reactions Displacement Reaction Chemical reaction in which an atom or molecule displaces an atom or group of atoms from a compound X + YZ → Y + XZ (X displaces Y) Fe + CuSO4 → Cu + FeSO4 (Fe displaces Cu) Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 7  Section 9.1 Types of Chemical Reactions Exchange Reaction Chemical reaction in which two substances exchange parts with one another and form two different substances AX + BY → AY + BX (A and B are exchanging with each other) AgNO3 (aq) + NaCl (aq) → AgCl (s) + NaNO3 (aq) (Ag and Na are exchanging with each other) Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 8  Section 9.1 Types of Chemical Reactions Combustion Reaction Chemical reaction between a substance and oxygen (usually from air) that proceeds with the evolution of heat and light (usually from a flame) C3H8 + 5O2 → 3CO2 + 4H2O *Often combustion reactions will produce carbon dioxide and water, but that isn’t a technical requirement. Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 9  Section 9.2 Redox and Nonredox Reactions Redox Reactions: We will not cover determining oxidation numbers! Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 10  Section 9.2 Redox and Nonredox Reactions Oxidation–reduction (redox) chemical reaction: Chemical reaction in which there is a transfer of electrons from one reactant to another reactant Nonoxidation–reduction (nonredox) chemical reaction: Chemical reaction in which there is no transfer of electrons from one reactant to another reactant Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 11  Section 9.3 Terminology Associated with Redox Processes Redox Characteristics In a redox reaction, one reactant undergoes oxidation, and another reactant undergoes reduction – Oxidation: A reactant loses one or more electrons – Reduction: A reactant gains one or more electrons Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 12  Redox Reaction Zinc has lost electrons, so it has been oxidized (by Cu2+). Cu2+ has gained electrons, so it has been reduced (by Zn). https://www.britannica.com/science/oxidation-reduction-reaction  Section 9.3 Terminology Associated with Redox Processes Table 9.1 - Summary of Redox Terminology in Terms of Electron Transfer Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 14  Section 9.1 Types of Chemical Reactions What Causes a Chemical Reaction to Take Place? A Certain Set of Conditions! Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 15  Section 9.4 Collision Theory and Chemical Reactions These Conditions are Described by: Collision Theory Molecular collisions Activation energy Collision orientation Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 16  Section 9.4 Collision Theory and Chemical Reactions Molecular Collisions Reactant molecules, ions, or atoms must come in contact (collide) with one another in order for any chemical change to occur Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 17  Section 9.4 Collision Theory and Chemical Reactions Activation Energy Minimum combined kinetic energy that colliding reactant particles must possess in order for their collision to result in a chemical reaction Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 18  Section 9.4 Collision Theory and Chemical Reactions Collision Orientation Reaction rates are sometimes very slow because reactant molecules must be orientated in a certain way in order for collisions to lead successfully to products Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 19  Section 9.4 Collision Theory and Chemical Reactions Figure 9.6 - Reaction of NO2 and CO to Produce NO and CO2 Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 20  Section 9.1 Types of Chemical Reactions Endothermic vs. Exothermic Reactions Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 21  Section 9.5 Exothermic and Endothermic Chemical Reactions Exothermic Chemical Reaction Chemical reaction in which energy is released as the reaction occurs Energy is a “product” of the chemical reaction Example - Burning of fuel Products are more stable than the reactants Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 22  Section 9.5 Exothermic and Endothermic Chemical Reactions Figure 9.7(a) - Exothermic Chemical Reaction unstable stable Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 23  Section 9.5 Exothermic and Endothermic Chemical Reactions Endothermic Chemical Reaction Chemical reaction in which a continuous input of energy is needed for the reaction to occur Energy is a “reactant” of the chemical reaction Example - Photosynthesis of plants – Additional energy must be supplied from external sources as the reaction proceeds – Products are less stable than reactants Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 24  Section 9.5 Exothermic and Endothermic Chemical Reactions Figure 9.7(b) - Endothermic Chemical Reaction unstable stable Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 25  Section 9.6 Factors That Influence Chemical Reaction Rates Chemical Reaction Rate The rate at which reactants are consumed or products produced in a given time period in a chemical reaction Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 26  Section 9.6 Factors That Influence Chemical Reaction Rates Factors Affecting Reaction Rates 1. Physical nature of the reactants 2. Reactant concentrations 3. Reaction temperature 4. Presence of catalysts Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 27  Section 9.6 Factors That Influence Chemical Reaction Rates Physical Nature of Reactants Includes the physical state of each reactant (solid, liquid, or gas) and the particle size – Reaction rate is generally faster between liquid-state reactants than between solid-state reactants – Reaction rate is fastest between gaseous-state reactants Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 28  Section 9.6 Factors That Influence Chemical Reaction Rates Reactant Concentrations An increase in the concentration of a reactant causes an increase in the rate of the reaction – There are more molecules of that reactant present in the reaction mixture; thus, collisions between this reactant and other reactant particles are more likely Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 29  Section 9.6 Factors That Influence Chemical Reaction Rates Reaction Temperature Reaction rate increases as the temperature of the reactants increases The increased molecular speed causes more collisions to take place in a given time Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 30  Section 9.6 Factors That Influence Chemical Reaction Rates Presence of Catalysts Catalyst: A substance that increases a chemical reaction rate without being consumed in the chemical reaction – Increases reaction rates by providing alternative reaction pathways that have lower activation energies than the original, uncatalyzed pathway Enzymes are the catalysts in the human body Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 31  Section 9.6 Factors That Influence Chemical Reaction Rates Figure 9.10 - Functioning of Catalysts Return to TOC Copyright ©2016 Cengage Learning. All Rights Reserved. 32