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Kinetics of homogeneous reaction CHAPTER 2
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IDEAL REACTORS HAVE THREE IDEAL FLOW OR CONTACTING PATTERNS.
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We know that: -rA= f [temperature depend term, concentration depend term] As an example: -RA=-1/V (DNA/DT)=(AMOUNT OF A DISAPPEARED)/(VOLUME*TIME)= [MOL/(M3.S)]
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ELEMENTARY REACTION
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NONELEMENTARY REACTION WE ASSUME THAT A SEQUENCE OF ELEMENTARY REACTION OCCURRING BUT WE CANNOT MEASURE OR OBSERVE THE INTERMEDIATE FORMED! FREE RADICALS/ IONS AND POLAR SUBSTANCE /TRANSITION COMPLEXES / NON CHAIN AND CHAIN REACTIONS MOLECULES
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Search for the reaction mechanism TESTING KINETIC MODELS (WE HAVE TWO LIMITATIONS) HYPOTHESIZE THE EXISTENCE OF EITHER OF TWO TYPES OF INTERMEDIATES: 1. STEADY STATE APPROXIMATION D[X]/DT=0 2. THE INTERMEDIATE IS IN EQUILIBRIUM WITH ITS REACTANTS
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Activated energy (E) has related with temperature. The temperature dependency of reactions is determined by the activated energy and temperature level of the reaction as illustrated in fig. (1-1). ARRHENIUS LAW R1=F1(TEMP.).F2(COMP.)=KF2(COMP.) ARREHENIUS LAW: K=K0E-E/RT [E]=JOULE/MOLE
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ACTIVATED ENERGY AND TEMPERATURE DEPENDENCY
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THERE ARE THREE AREAS OF INVESTIGATION OF A REACTION, THE STOICHIOMETRY, THE KINETICS AND THE MECHANISM. - STOICHIOMETRY CAN TELL WHETHER WE HAVE A SINGLE REACTION OR NOT. - STOICHIOMETRY CAN SUGGEST WHETHER A SINGLE REACTION IS ELEMENTARY OR NOT, THERE IS NO ELEMENTARY REACTIONS WITH MOLECULARITY GRATER THAN THREE. N2+3H2 2NH3 - USING PRINCIPLE OF MICROSCOPIC REVERSIBILITY. - FOR MULTIPLE REACTIONS WITH INCREASING TEMP.
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PREDICTABILITY OF REACTION RATE FROM THEORY - CONCENTRATION-DEPENDENT TERM EXPERIMENTALLY FOUND RATE EXPRESSION IS OFTEN USED TO INVESTIGATE THE ENERGIES OF THE INTERMEDIATE OF THE REACTION. - TEMPERATURE-DEPENDENT TERM WITH ASSUMPTION THAT WE KNOW THE MECHANISM AND WHETHER OR NOT IT IS ELEMENTARY WE MAY THEN PREDICT ACTIVATED ENERGY, BUT THIS PROCEDURE HAS A LOT ERROR! - USE OF PREDICTED VALUE IN DESIGN FOR ENGINEERING DESIGN, EXPERIMENTALLY FOUND RATE SHOULD BE USED IN ALL CASES.
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