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Lecture 2

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Lecture 2 Kinetic: Include: Reaction rate, order of reaction, temperature dependence of the reaction. The industrial chemical reaction can be divided in the following groups: 1) According the type of chemical process (introduce of energy for the reaction) -Thermal process-Electrochemical process-Biochemical Process The thermal processes are the widely used 2) Classification according the system. a- Homogenous b- Heterogenous 3) Classification according of method of working. a- Isothermal (at co
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  Lecture 2  Kinetic : Include: Reaction rate, order of reaction, temperature dependence of the reaction. The industrial chemical reaction can be divided in the following groups:1)According the type of chemical process introduce of energy for the reaction)!Thermal process! lectrochemical process!#iochemical $rocessThe thermal processes are the widely used%)&lassification according the system.a! 'omogenous b! 'eterogenous() &lassification according of method of woring.a! Isothermal at constant temperature) b! Adiabatic without heat change with the surrounding if the reaction vessel is able to absorb or supply the heat of reaction*.if not temperature change with time)c! +on isothermal not adiabatic) &lassification according the type of reaction.a! -imple reaction, irreversible forward reaction) k   A R   →  b! &omplicated reactionI! -imultaneous reaction 1% k k   A R A S    →  →  The yield of R is reduced by the simultaneous side reaction - II! &onsecutive reaction 1% k k   A B C    →  →  # undergoes a consecutive reaction to unwanted &1R AR A-#   A&  Lecture 2 III! &omplicated consecutive reaction 1%(%//%%%%(( .:&hlorination of #en0ene&&&&&& k k k   A B R A R S  A S T etc Ex H Cl H Cl HCl  H Cl Cl H Cl HCl  H Cl Cl H Cl HCl  +  →+  →+    →+    → ++    → ++    → + I! Reversible reaction forward and bacward reaction) 1% k k   A B ˆˆˆ†‡ˆˆˆ /! &lassification according the reactor type  Stoichiometry and Reaction Rate ã -toichiometry and 2imiting -pecies aA bB cC dD +    → + ã Reaction Rate  3or homogeneous reactions, it is defined as the number of molecules disappeared or produced per unit time per unit volume. 4mol5s.dm ( 6  Its definition depends on a reactor flow condition. 3or a constant volume batch reactor: ( ) 51  A A A A d N V dN dC r V dt dt dt  − = − = − = −  -elect one species, usually the limiting species as the basis of calculation C  A B D r r r r a b c d  − −= = = %   #ATR -A#  Lecture 2  Reaction Rate Constant & Rate Laws 'ow the rate of a reaction is determined7 aA bB cC dD +    → + ã Temperature ã &oncentration of reacting species ),,...)  A A n A B r k T f C C  − = ã Rate law   ,,...) n A B  f C C  ã -pecific reaction rate constant) : )  A k T  )  E  RT  A k T Ae − = 8nder a specific temperature,   A  can be taen as a constant  Reaction Order  The Reaction 9rder   A A A B r k C C  α β  − =  The reaction order of A is  .  The reaction order of # is β .  The overall reaction order is ;  β  <ero order reaction  A A r k  − =  3irst order reaction  A A A r k C  − =  -econd order reaction %  A A A r k C  − =  Third order reaction (  A A A r k C  − =  Elementary Reactions 3or the reaction in which the reaction orders of each species is identical with the stoichiometric coefficient, i.e. %%%% %%  NO O NO iselementaryCO Cl COCl is not elemetary +    →+  →  Molecularity: The no. of species involved in the rate limiting step of the reaction unimolecular, bi, tri, etc. =: ((((  NaOH CH C CH CH C CH NaBr  + − −    → − − + The rate law is determined from e>perimental observation TBB TBB r kC  − = (   &' ( &' ( #r9'  Lecture 2 The reaction is irreversible, homogenous, li?uid phase, first order and nonelementary  Reversible Reaction The gas phase reaction 11%1@%% %)) k k  C H C H H  Benzene dipenyle + ˆˆˆ†‡ˆˆˆ  elementary and reversible  1  and   % will be defined with respect to #en0ene #) % %%11%  B B B B B D H  r formed k C or r formed k C r re!erse k C C  − = = −= The net rate of formation of # %%% ,,,%1%%%11%11% tan)  B B net B formed B re!erse B B D H  B D H  D H  B e e r r r r r k C k C C k k C C C k C C  k k C #ere $ e %ilibri%mcons t  $ k  = = +− = −  = − ÷    = − = ÷ ÷    Nonelementary Reaction The reaction %%% %%15%1'#r %( %isnonelementary with rate lowr and the reaction,  H Br  HBr Br   H Br HBr k C C k C CH CHO CH CO +=→ + ˆˆ†‡ˆˆ At T/@@ o & is (5% order with respect to &' ( &'9 (( (5% CH CHO CH CHO r kC  − = In many gas solid cataly0ed reaction is preferable to tae the partial pressure.i.e. ( ) /%( )51 C B & & C C C B B C H CH CH C H C H C B & k & & & k r k & k &  +−′− =+ + ˆˆ†‡ˆˆ C  r   ′−  as a function of conversion, replace $ i  with conc. 8sing the ideal gas law ) C C  A B A  & C RT r r   ρ  =′− = − Bhere!r  A per unit volume  A r   ′−  per unit weight of catalyst  B  ρ   bul density of catalyst 
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