Week 3 Chemistry Book Notes
Week 3 Chemistry Book Notes Chem 143
Popular in General Chemistry 2
verified elite notetaker
Popular in Chemistry
This 4 page Class Notes was uploaded by Cassidy Zirko on Saturday February 13, 2016. The Class Notes belongs to Chem 143 at University of Montana taught by Dr. Cracolice in Spring 2016. Since its upload, it has received 20 views. For similar materials see General Chemistry 2 in Chemistry at University of Montana.
Reviews for Week 3 Chemistry Book Notes
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 02/13/16
Week 3, Chem 143, Prof Cracolice Chapter 47: How Do Catalysts Speed Up Chemical Reactions? 2/8/16 47.1 What Are Particular Level Processes by which Reactions Occur? Reaction mechanism collection of individual molecular steps that comprise a chemical reaction rate laws given are a small list of possible mechanisms Elementary Step chemical change in a reaction mechanisms Sum of all elementary steps gives overall reaction Reaction intermediate a species that is produced in an elementary step and consumed in a subsequent step and does not appear in overall reaction Molecularity number of reacting particles Unimolecular elementary step in which one particle changes or decomposes Bimolecular when 2 particles react Termolecular elementary steps with three or more particles What are the Elementary Steps that Make up a Reaction? o X+Y in a rate reaction reaction order with respect to A and B o No directly related to reaction stoichiometry o Reaction rate depends on the reactant concentration at macroscopic level o Elementary rate law is directly related to reaction stoichiometry ¿ T o Rate= −1 ∆ A [¿]= −1 ∆ [ ]=k[ A] [B] y a [ ] b ∆ [ ] o a and b reaction order with respect to A and B same coefficients of those species in elementary step equation o slowest step in reaction mechanism determines the rate of the overall reaction o reaction cant go any faster than slowest step o rate laws expressed in terms of measurable concentrations o find overall rate equation reaction intermediates that appear in the rate determine step must be replaced by equivalent involving only reaction o rate constant in final equation, K derived from rate constants of elementary step K 1 forward K=K 2 K 2reverse 47.2 What is a Catalyst and How does it Function? Catalyst provides alternate route for reactants to change to products E aactivation energy with catalyst, activation energy is lowered Week 3, Chem 143, Prof Cracolice Termolecular collisions are unlikely to occur Overall reaction stoichiometry results from the sum of elementary steps Catalyst vs. Intermediate o Intermediate product in an early step of a reaction mechanism and reaction in later step o Catalyst begins as a reactant and reappears as a product Negative Catalysts, inhibitors substances that interfere with normal reaction path from reactants to products, forcing reaction to a higher activation energy that is slower How do Biological Catalysts Function? o Enzyme controls chemical reaction in living system o Allows living systems to preform and control at body temperature a chemical reaction o Substrate reactant that the enzyme helps to convert to product o Active site location that binds the enzymes substrate during reaction that follows o Enzymes are specific with shape and polarity o Induced Fit Model show how enzyme molecules function o Intermolecular attractions distinct shape and induced final fit o Fit cause bond at reacting point on substrate to become strained o Inhibitor substrate that remains bound to an enzyme o Three different energy barriers Formation of substrate enzyme complex Substrate changing to products Carries products – enzyme complex How does an Automobile Catalytic Converter Function? o Catalytic Converter pollution reducing device integrated with in exhaust system of automobiles that are powered by an internal combustion engine o Unspecified metal catalyst is used, usually platinum Chapter 48: How Do Chemists Use Symbols and Mathematics to Describe the Characteristics of an Equilibrium System? 2/10/16 48.1 What Conditions Characterize Equilibrium Systems? Equilibrium systems conditions o Change is reversible and can be represented by an equation with double arrow o Equilibrium is in a closed system, no substance can enter or leave the intermediate vicinity of the equation o Equilibrium is dynamic reversible changes that occur constantly without energy o Things are equal in equilibrium are the forward rate of change and the reverse rate of change amount of substances don’t have to be equal Week 3, Chem 143, Prof Cracolice Reactant concentrations decrease forward reaction rate declines For any reversible reaction opposing reactions are occurring at different rates faster becomes slower and slower becomes faster, opposite rates become equal at equilibrium Ratio of concentrations will always be equal to K /Kfatrequilibrium 48.2 How are Equilibrium Concentrations Related in an Equilibrium System? Equilibrium constant, K any equilibrium at a temperature the ratio of product concentration of the species on the right side of K, raised to the power equal to the coefficient to the product concentration on the left side of the equation are constant c d K= [C] [D] ex. [ A] [B] b for equation aA+bB cC+dD equilibrium can happen with solid and liquid phases when writing an equilibrium equation constant expression, only use the concentration of the species of the gas phase, not those species who are in solid or liquid phases How is the Equilibrium Constant Written in Terms of Pressure? o K che equilibrium constant written in terms of concentration o K Specifies relationship requiring knowledge of pressure and concentration relationship o K =K x R T ∆ n or K =K x R T ∆ n p c c p Why do Equilibrium Constants have No Units? o Law of Mass Action Rate of a chemical reaction is the product of concentration of reactants to the power of coefficients o Activity a =xX]/1M where X is some species 48.3 What is the Significance in the Value of an Equilibrium Constant? Equilibrium constant is a ratio in fraction form Near Zero denominator and large K means the reaction is favored in the forward direction Near zero numerator equation is favored in reverse direction How Does Changing a Chemical Equation Change the Equilibrium Constant? o Every equilibrium expression must be associated with a specific equilibrium equation o Inverse K relationships for opposite reaction is true fro any reaction that can occur in both directions o If reaction coefficients are multiplied by some number, equilibrium constant is raised to a power equal to that number o The K value for a reaction is that the sum of 2 reactions is the product of K values for those reaction 48.4 Why are Solids and liquids excluded from Equilibrium Constant Expressions? The concentration for a pure liquid and solid are constant Week 3, Chem 143, Prof Cracolice Heterogeneous equilibrium reaction involves species that exist in different phases Chapter 49: How are Equilibrium Constant Values Determined? 2/11/16 49.1 How Are Equilibrium Constant Values Determined? Find the equilibrium concentration of each species either numerically or algebraically Insert these values into the equilibrium constant expression and solved for desired value Use ICE table o Iinitial Concentration o C change in Concentration o EEquilibrium Concentration Gain of moles is designated with +, loss with – in the change of concentration row When using quantity algebra, from equilibrium concentration of a species, the solved leads to change in concentration with respect to the that species, then you subtract from initial concentration to get concentration at equilibrium
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'