CHEM 0120 1nd Edition Lecture 4 Outline of Last Lecture I Dispersion Forces II Dipole Dipole Interactions III Hydrogen Bonding Outline of Current Lecture I Collision Theory II Rate Constant III Arrhenius Collision Theory IV Similar to Example 13 7 V Rate Order VI Initial Rate Method Determines Order of Reaction Current Lecture Continued from January 6th Lecture B Increasing Rate of Reaction 3 Surface Area of Reactant 4 Temperature C Rate 1 A a t 1 B b t 1 C c t 1 D d t 1 A A f A i I II 2 Always want to convey rate as a positive value Collision Theory a reaction occurs when a collision occurs at proper orientation and sufficient energy greater than Ea Rate constant k zfp A z number of collisions These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute B E a Rt f e energy fraction of collisions with energy sufficient to overcome activation J mol K t temperature Kelvins 1 temperature exponent e f k 2 stability of activation complex Ea activation energy R 8 31 III E a Arrhenius Collision Theory k A e Rt A zp Relatively temperature independent ln k ln A e E a 1 R t plotting ln k vs IV V 1 t will provide Ea 1 1 t1 t 2 k 2 Ea ln k1 R k1 k2 rate constant of respective temperatures t1 t2 temperature Kelvins Similar to Example 13 7 Temp 1 759K k 1 05 10 3 Temp 2 836K k 2 14 10 2 1 1 759 K 836 K 2 14 10 2 Ea ln 1 05 10 3 8 31 J mol K Ea 2 06 105 J mol aA bB cC dD Rate k A m B n m n are determined experimentally unless in the case of an elementary reaction 1 step to products when m n are determined by the stoichiometric coefficients Rate k NO 2 H2 Second order with respect to NO First order with respect to H2 Third order reaction VI Initial rate method determines order of reaction 13 54 2NO g O2 g 2NO2 g Rate k NO m O2 n Trials NO i 1 0 0125 2 0 0250 3 0 0125 m n Rate 2 k 2 NO O2 m n O2 i 0 0253 0 0253 0 0506 Rate 1 k 1 NO O2 Always place higher concentration on top mol 0 112 0 0250 m 0 0253 n L s mol 0 0281 0 0125 m 0 0253 n L s m 2 for NO 4 2m 0 0125 m 0 0506 n mol 0 0561 L s n 1 for O 2 2 2n NO O2 Rate k Rate 0 0281 0 112 0 0561