cairo university faculty of engineering chemical engineering department organic chemical process...
TRANSCRIPT
CAIRO UNIVERSITYCAIRO UNIVERSITYFACULTY OF ENGINEERINGFACULTY OF ENGINEERINGCHEMICAL ENGINEERING DEPARTMENTCHEMICAL ENGINEERING DEPARTMENT
Organic Chemical Process Industries
TA. Jasmine AmrEng. Hassan El- Shimi
Section 1
Wednesday, September 22nd, 2010
Today’ AgendaToday’ Agenda General view on Organic Industries Course contents Marks Review on Chemical Kinetics Sheet 1
Course ContentsCourse Contents
Lectures Sections
Organic Technology (Overview)
o Nitrationo Nitrobenzene
o Dinitrobenzene
o TNB
o Aniline industry
o TNT, and ….
Sulfonation Intro to Petrochemical
Industry
Review on Chemical Kinetics (2 sections)
Nitration Thermodynamics ( 2 sections)
Peroxide value Saponification value O & G Estimation BOD5 & COD Dying
Mwt. Determination
Laboratory
Prof. Dr. SamiaProf. Dr. HodaProf. Dr. Sahar
TA. Jasmine AmrEng. Hassan El-
Shimi
MarksMarks (acceptable to change) (acceptable to change)
Total marks = 150 markFinal exam : 90 markYear work : 60 marko 1st midterm : 30 marko 2nd midterm : 10 markso Oral exam : 10 markso Lab : 10 mark
Chemical Reaction KineticsChemical Reaction KineticsFor any reaction A+B → C (product)Rate of reaction α no. of collisions
between molecules A, B.Rate of reaction α concentration of A, BAs rA α CA CB, hence rA = k CA CB
Where k: specific rate constantRate of reaction is rate of consumption or
production of component (i) rA= - dCA/dt = - dCB/dt = +dCC/dt = kCACB
If aA+bB → cC+dD (balanced equation)Hence, rA = k CA
a CBb (rate equation)
Where, a: order of reaction w.r.t. reactant (A) and b: order of reaction w.r.t. reactant (B)
Overall order of reaction = a+b
In case of reversible reaction: aA+bB ↔ cC+dDRate eq.: rA= kf CA
aCBb – kb CC
cCDd
Order of reaction= (a+b) – (c+d)
Mechanism of reactionMechanism of reaction
Elementary Reactions Non-elementary Reactions
Reactions occur in a single step and the rate expression is suggested from the stiochiometric equation.
2A+B → R+S
rA = k CA2CB
Reactions which we observe as a single reaction, but in the real, it’s the result of a sequence of elementary reactions and the rate equation can’t be detected from the stiochiometric equation.
2A+B → R+S In fact: A+B → AB AB+A → A2B +S A2B → R These 3 steps are called: the
reaction mechanism Rate eq. = rate eq. of determining
step (slowest step) ≠ kCA2CB
Arrhenius EquationArrhenius Equation
K= Ao e –E/RT
K: specific rate constantAo: Arrhenius constantE: activation energyT: absolute temperature (Kelvin or oR)R: universal gas constant= 8.314 J/gmole.K or
R= 0.082 lit.atm/gmole.K or R= 1.987 cal/gmole. K = 10.73 Btu/Ib. R
Dependence of Rx Rate on Concentration:
r = k CAn CB
m; n & m order of Rx
If B is in large excess; CB ≈ constant, i.e. –dCB/dt ≈ 0, hence
CBm = constant and rA = k’ CA n, where
k’= k CBm, and it’s easy to get (n).
Molecularity:o It’s the number of reactant molecules in the
stiochiometric equation (Elementary Rx) OR number of molecules in the rate determining step (Non-elementary Rx).
o N.B.: if order of Rx = Molecularity, the reaction is called simple order reaction.
Sheet 1Sheet 1Problem no. 1
A → B, r = kCAn; n=?
1) Assume zero order reaction (n=0)
Hence, r= - dC/dt = k[C]n=0 = k
Get CA-CAo = - k*t
Hence, CA=CAo – k*t
CA
t
Slope = k
2) Assume 1st order reaction ( n=1)
r= -dCA/dt = k[CA]
-dC/[C] = k dt
Hence, Ln CA- Ln CAo = -k*t
Finally, ln CA = ln CAo –k*t
Ln CA
t
Slope = k
3) Assume 2nd order reaction ( n=2)
r= -dCA/dt = k[CA]2
-dC/[C]2 = k dt
Hence, 1/CA- 1/CAo = k*t
Finally, 1/CA = 1/CAo + k*t
1/CA
t
Slope = k1/CAo
a) Plot C vs t
b) Plot 1/C vs t
The order of reaction is 2nd order
Slope = k = 1.415E-06 lit/gmole. Sec
Problem no. 2Problem no. 2Given E= 75000 calK at 650oC and 500oCHence, T1= 923ok & T2= 773ok
Since k= Ao e-E/RT
k1= Ao e-E/R(773) → 1
k2= Ao e-E/R(923) → 2
k1/k2 =
k1/k2 =
Since E= 73000 cal & R= 1.987 cal/gmol .k
Thus, k1/k2 = 2/3 and k1=(2/3) k2
i.e. k2 > k1 , thus the reaction at (T2= 650oC) is faster than the reaction at (T1= 500oC).
Chemical Third Year, CHE2012Any Question
For any problem, please contact me:
Eng. Hassan El- ShimiE-mail: [email protected]
Mobile: 011 80 87 86 2
Thank You