化学大学英文课件.pdf

Went over the syllabus Know what s in there Read Handouts 1 and 2 should be chem 101 review Chapter 16 sections 1 4 Practice Problem set 1 will be posted by Wednesday You should be able to solve questions 1 and 2 after today s lecture Problem sets are not handed in or marked but I highly recommend that you solve them on your own or at least try doing so Your new year s resolution should be studying this term Speed Bump by Dave Coverly Mine is to try and improve on my handwriting Past experience suggests you have a better chance than me Bizarro by Dan Piraro 1 Math review logarithm and natural logarithm Logarithm base 10 log x y x 10y Natural logarithm ln x y x ey Some mathematical operations involving log and ln log xa a log x ln xa a ln x log x 1 log 1 x ln x 1 ln 1 x log xy log x log y ln xy ln x ln y log x y log x log y ln x y ln x ln y Make sure your calculator has these four functions log x ln x 10 x ex or expx You ll need them on exams 2 Unit 1 Reaction kinetics Rxn rates 16 1 16 2 Rate laws and reaction order 16 3 Integrated rate laws 16 4 Arrhenius model 16 5 16 6 Reaction mechanisms 16 7 Catalysis 16 8 3 Kinetics is concerned with the reaction progress or pathway How do we get from the initial state reactants to the final state products How fast rate of rxn Concentration effects rate equation How exactly it happens mechanism Other effects temperature catalysis 4 Rate of rxn Rate of rxn change in concentration time interval Products and or reactants depending which is monitored NO2 g NO g 1 2 O2 g How do concentrations change Based on stoichiometry NO2 NO O2 1 2 final initial So reactants is negative ve Add ve sign to satisfy the equality The ve sign should make sense as NO2 is being consumed 5 Reaction rate is always a ve quantity To get the rate you need to divide by the time Rate NO2 t NO t O2 1 2 t Rxn rate is specific to a rxn you need a balanced rxn and therefore is stoichiometry dependent Rate of formation or rate of disappearance are not specific for a reaction and are stoichiometry independent Rates of formation or disappearance are not necessarily equal to the reaction rate 6 7 In general aA bB dD eE Rxn rate A a t B b t D d t E e t Rxn rate units concentration time M s mol L s M s 1 8 For the rxn between NH3 and O2 gases at high temperatures the rate of disappearance of NH3 is 3 5 x 10 2 M s at t 20s Calculate the rate of formation of H2O at t 20s NH3 O2 NO H2O unbalanced 4 NH3 5 O2 4 NO 6 H2O balanced Rate of disappearance