DOC PREVIEW
TAMU CHEM 102 - Exam 2 Study Guide
Type Study Guide
Pages 5

This preview shows page 1-2 out of 5 pages.

Save
View full document
View full document
Premium Document
Do you want full access? Go Premium and unlock all 5 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 5 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 5 pages.
Access to all documents
Download any document
Ad free experience

Unformatted text preview:

CHEM 102Exam 2 Study Guide: Lectures 1 - 7Lecture 1Chemical KineticsDescribe what the components of chemical kinetics are. What is average rate of reaction? What is instantaneous rate? What are the factors that affect reaction rates? Explain the Collision Theory of Reaction Rates. What are rates directly related to? What is the Rate Law set-up? How do you determine Rate Law? Chemical kinetics components:- the reaction is non-spontaneous and very slow- study chemical reaction rates: how quickly reactants are gone and products are made- reaction rate: change in amount of products or reactants in a certain time amount- study of reaction mechanisms: steps that go from reactants to products- reaction mechanism: displays reactions broken down to the molecular levelAverage rate of reaction: negative version of the slope of concentration over time graph Instantaneous rate: the negative version of the tangent slope of concentration over time graph but at a specific graphFactors that affect reaction rates:- surface area increases as reaction rate increases - usually, reaction concentration increases as reaction rate increases (the more molecules, the more collisions)- a temperature increase makes any reaction rate increase (the collisions in a given time increases and additional molecules have smaller force)- catalysts increase reaction rates (lowers activation energy)Collision Theory of Reaction Rates: In order for chemical reactions to happen,...- Reactants (at the molecular, atomic, or ionic level) have to run into each other. When theydo, the reactants have to have minimal energy and a certain position at the time they run into each other.Rate Law: Rate=k[A]x[B]y(k=specific rate constant, x & y= reaction order in relation to A & B)- figured out from the experiment, not the balanced net equation, usually positive or zero but can be in negative or fractions- have to do many experiments, measuring the initial rate based as a function of several concentrations of reactants (can be checked in different ways, such as pressure or spectroscopic) and you figure out reactant orders by comparing the different experiments- in order to find k, you must calculate from one set of reaction-rate data of reactantconcentrations (can be any data set)Lecture 2 Name the effects 0, 1, 2, 3, 1/2 exponents have on two initial rates. What are the components of rate constant “k”. What does the integrated rate equation do? Give the equations for Zero order, 1st order, and 2nd order reactions.Exponent effects on two initial rates:0: no difference in rate with changing amount of concentration1: rate increases only by the change in concentration sum2: the concentration amount goes up by 2 and the rate goes up by 43: the concentration amount goes up by 2 and the rate goes up by 81/2: the concentration amount goes up by 2 and the rate goes up by 1.4Rate constant “k”:- is only for specific reactions and from experimental data- does NOT change as initial concentration or time (during a reaction) changes- DOES change as temperature changes or if a catalyst is or is not there- there is no set unit, conditional in reaction order overall (concentration overall) (example is 1st order reaction: 1/sec)The Integrated Reaction Equation: shows concentration as related to time, so can find reactants and products at a certain time. Also, can find half-life f products. However, this DOES depend on reaction order overall. Zero order: (Rate= k[A]0) [A]= -akt + [A]o or t1/2 = [A]o / 2ak (negative slope!)1st order: (Rate= k[A]1) ln[A] = -akt + ln[A]o (negative slope!)2nd order: (Rate= k[A]2) 1/[A] = akt + 1/[A]o or t1/2 = 1/ak[A]o (positive slope!)([A]o= initial concentration)Lecture 3What is the role of the catalyst? What are the components of the Transition State Theory (activation energy)? Catalyst: increases rate of reaction!Transition State Theory- the chemical reactions that are dealing with breaking and making bonds (the energy need to break them)- Activation energy (Ea): the minimal energy reactants need in order to make an activated complex, it is included in both endothermic and exothermic, rates of reactions are each different because of Ea differences (for example, the lower the Ea, the quicker the reaction)- the amount of Ea can not be found from enthalpy of reaction Lecture 4What is the Arrhenius Equation? What algebraic equation is used to help break down the Arrhenius Equation? What is a elementary reaction? What is a reaction mechanism? Name the guidelines for making a reaction mechanism (6). What is the rate-determining step (RDS)? Arrhenius Equation: k= Ae-Ea/RT (know correct R!)- When there are TWO different TEMPERATURES in 1st order: ln(k2/k1) = Ea/R[1/T1 -1/T2]Breaking down the Arrhenius Equation: y = mx + bElementary Reactions: single occurrence at molecular position, so the reaction order is the same as the number of molecules in a reactant (coefficient); there’s one-molecule (unimolecular), two-molecular (bimolecular), three-molecular (termolecular) reactions; they must add up to show overall equationReaction Mechanism: series of elementary steps that forms products, so essentially the overall reaction; they show the breaking and forming of products, most being more than one step; the slower step id the rate determining step; the rate law does not have intermediates but can have products if mechanism says to. Making reaction mechanism:- find the net reaction- Rate Law for a step can be found using stoichiometry - chemicals made then used up are the INTERMEDIATES- mechanism has to be steady with the experimental rate law- the elementary steps have to physically reasonable unless evidence dictates otherwise and then bimolecular is used over termolecular stepsRate determining step (RDS): slowest step during a mechanismLecture 5Is a mechanism reaction any different if it has a fast initial step? So how does the catalyst fit in a mechanism (review what a catalyst is)? What is the difference between a homogeneous and heterogeneous catalyst? Name a biological catalyst. YES, a fast initial step does affect a mechanism reaction.Catalyst:- chemical that increases the reactions rate that is NOT consumed (so is not in the balancedequation)- increases the speed of both forward and reverse equation - IS part of rate law- LOWERS the activation energy by making a dissimilar reaction mechanismA homogeneous catalyst is in the same phase as the reactants (first reactant then appears as product in the


View Full Document

TAMU CHEM 102 - Exam 2 Study Guide

Type: Study Guide
Pages: 5
Download Exam 2 Study Guide
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view Exam 2 Study Guide and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Exam 2 Study Guide 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?