topic d: arrhenius equation and catalysts. arrhenius said the reaction rate should increase with...
TRANSCRIPT
![Page 1: TOPIC D: ARRHENIUS EQUATION AND CATALYSTS. Arrhenius Said the reaction rate should increase with temperature. At high temperature more molecules have](https://reader035.vdocuments.net/reader035/viewer/2022062309/56649f175503460f94c2d342/html5/thumbnails/1.jpg)
TOPIC D:ARRHENIUS EQUATIONAND CATALYSTS
![Page 2: TOPIC D: ARRHENIUS EQUATION AND CATALYSTS. Arrhenius Said the reaction rate should increase with temperature. At high temperature more molecules have](https://reader035.vdocuments.net/reader035/viewer/2022062309/56649f175503460f94c2d342/html5/thumbnails/2.jpg)
Arrhenius• Said the reaction rate should increase with temperature.• At high temperature more molecules have the energy
required to get over the barrier.• The number of collisions with the necessary energy
increases exponentially.
![Page 3: TOPIC D: ARRHENIUS EQUATION AND CATALYSTS. Arrhenius Said the reaction rate should increase with temperature. At high temperature more molecules have](https://reader035.vdocuments.net/reader035/viewer/2022062309/56649f175503460f94c2d342/html5/thumbnails/3.jpg)
Arrhenius• Number of collisions with the required
Energy = ze-Ea/RT
• z = collision frequency• e is Euler’s number (opposite of ln)• Ea = activation energy• R = ideal gas constant (8.314 J/K·mol)• T is temperature in Kelvin
•e-Ea/RT represents the fraction of collisions with energy
>Ea at temperature T.
![Page 4: TOPIC D: ARRHENIUS EQUATION AND CATALYSTS. Arrhenius Said the reaction rate should increase with temperature. At high temperature more molecules have](https://reader035.vdocuments.net/reader035/viewer/2022062309/56649f175503460f94c2d342/html5/thumbnails/4.jpg)
Problems• Observed rate is less than the number of collisions that
have the minimum energy.• Due to Molecular orientation• written into equation as p the steric factor.
![Page 5: TOPIC D: ARRHENIUS EQUATION AND CATALYSTS. Arrhenius Said the reaction rate should increase with temperature. At high temperature more molecules have](https://reader035.vdocuments.net/reader035/viewer/2022062309/56649f175503460f94c2d342/html5/thumbnails/5.jpg)
ON
Br
ON
Br
ON
Br
ON
Br
O N Br ONBr ONBr
O NBr
O N BrONBr No Reaction
![Page 6: TOPIC D: ARRHENIUS EQUATION AND CATALYSTS. Arrhenius Said the reaction rate should increase with temperature. At high temperature more molecules have](https://reader035.vdocuments.net/reader035/viewer/2022062309/56649f175503460f94c2d342/html5/thumbnails/6.jpg)
Two Requirements for successful collision
• The collision must have enough energy to produce the reaction [ >Ea ].
• The relative orientation of the reactants must allow formation of any new bonds.
• K = zpe-Ea/RT z = collision freq.
• P = steric factor (fraction of collisions with the correct orientation)
![Page 7: TOPIC D: ARRHENIUS EQUATION AND CATALYSTS. Arrhenius Said the reaction rate should increase with temperature. At high temperature more molecules have](https://reader035.vdocuments.net/reader035/viewer/2022062309/56649f175503460f94c2d342/html5/thumbnails/7.jpg)
•k = zpe-Ea/RT = Ae-Ea/RT
• A is called the frequency factor = zp
• This equation is in your packet:
• ln k = -(Ea/R)(1/T) + ln A
• Another line !!!!
• ln k vs 1/t is a straight line
• Slope m = -Ea / R
Arrhenius Equation
![Page 8: TOPIC D: ARRHENIUS EQUATION AND CATALYSTS. Arrhenius Said the reaction rate should increase with temperature. At high temperature more molecules have](https://reader035.vdocuments.net/reader035/viewer/2022062309/56649f175503460f94c2d342/html5/thumbnails/8.jpg)
![Page 9: TOPIC D: ARRHENIUS EQUATION AND CATALYSTS. Arrhenius Said the reaction rate should increase with temperature. At high temperature more molecules have](https://reader035.vdocuments.net/reader035/viewer/2022062309/56649f175503460f94c2d342/html5/thumbnails/9.jpg)
![Page 10: TOPIC D: ARRHENIUS EQUATION AND CATALYSTS. Arrhenius Said the reaction rate should increase with temperature. At high temperature more molecules have](https://reader035.vdocuments.net/reader035/viewer/2022062309/56649f175503460f94c2d342/html5/thumbnails/10.jpg)
Ex 12.7 Determining Activation Energy
• The reaction: 2N2O5 (g) → 4NO2 (g) + O2 (g)
was studied as several temperatures, and the following values of k were observed.
K (s-1) T (oC)
2.0 x 10-5 20
7.3 x 10-5 30
2.7 x 10-4 40
9.1 x 10-4 50
2.9 x 10-3 60
Calculate the value of Ea for this reaction.
![Page 11: TOPIC D: ARRHENIUS EQUATION AND CATALYSTS. Arrhenius Said the reaction rate should increase with temperature. At high temperature more molecules have](https://reader035.vdocuments.net/reader035/viewer/2022062309/56649f175503460f94c2d342/html5/thumbnails/11.jpg)
Catalysts• Speed up a reaction without being used up in the reaction.• Enzymes are biological catalysts.• Homogenous Catalysts are in the same phase as the
reactants.• Heterogeneous Catalysts are in a different phase as the
reactants.
![Page 12: TOPIC D: ARRHENIUS EQUATION AND CATALYSTS. Arrhenius Said the reaction rate should increase with temperature. At high temperature more molecules have](https://reader035.vdocuments.net/reader035/viewer/2022062309/56649f175503460f94c2d342/html5/thumbnails/12.jpg)
How Catalysts Work
• Catalysts allow reactions to proceed by a different mechanism - a new pathway.
• New pathway has a lower activation energy.• More molecules will have this activation energy.• Do not change E
![Page 13: TOPIC D: ARRHENIUS EQUATION AND CATALYSTS. Arrhenius Said the reaction rate should increase with temperature. At high temperature more molecules have](https://reader035.vdocuments.net/reader035/viewer/2022062309/56649f175503460f94c2d342/html5/thumbnails/13.jpg)
Lowering of Activation Energy by a Catalyst
![Page 14: TOPIC D: ARRHENIUS EQUATION AND CATALYSTS. Arrhenius Said the reaction rate should increase with temperature. At high temperature more molecules have](https://reader035.vdocuments.net/reader035/viewer/2022062309/56649f175503460f94c2d342/html5/thumbnails/14.jpg)
Catalysts Increase the Number of Effective Collisions
![Page 15: TOPIC D: ARRHENIUS EQUATION AND CATALYSTS. Arrhenius Said the reaction rate should increase with temperature. At high temperature more molecules have](https://reader035.vdocuments.net/reader035/viewer/2022062309/56649f175503460f94c2d342/html5/thumbnails/15.jpg)
Pt surface
HH
HH
HH
HH
Heterogenous Catalysts
• Hydrogen bonds to surface of metal.
• Break H-H bonds
![Page 16: TOPIC D: ARRHENIUS EQUATION AND CATALYSTS. Arrhenius Said the reaction rate should increase with temperature. At high temperature more molecules have](https://reader035.vdocuments.net/reader035/viewer/2022062309/56649f175503460f94c2d342/html5/thumbnails/16.jpg)
Pt surface
HH
HH
Heterogenous Catalysts
C HH C
HH
![Page 17: TOPIC D: ARRHENIUS EQUATION AND CATALYSTS. Arrhenius Said the reaction rate should increase with temperature. At high temperature more molecules have](https://reader035.vdocuments.net/reader035/viewer/2022062309/56649f175503460f94c2d342/html5/thumbnails/17.jpg)
Pt surface
HH
HH
Heterogenous Catalysts• The double bond breaks and bonds to the catalyst.
C HH C
HH
![Page 18: TOPIC D: ARRHENIUS EQUATION AND CATALYSTS. Arrhenius Said the reaction rate should increase with temperature. At high temperature more molecules have](https://reader035.vdocuments.net/reader035/viewer/2022062309/56649f175503460f94c2d342/html5/thumbnails/18.jpg)
Pt surface
HH
HH
Heterogenous Catalysts• The hydrogen atoms bond with the carbon
C HH C
HH
![Page 19: TOPIC D: ARRHENIUS EQUATION AND CATALYSTS. Arrhenius Said the reaction rate should increase with temperature. At high temperature more molecules have](https://reader035.vdocuments.net/reader035/viewer/2022062309/56649f175503460f94c2d342/html5/thumbnails/19.jpg)
Pt surface
H
Heterogenous Catalysts
C HH C
HH
H HH
![Page 20: TOPIC D: ARRHENIUS EQUATION AND CATALYSTS. Arrhenius Said the reaction rate should increase with temperature. At high temperature more molecules have](https://reader035.vdocuments.net/reader035/viewer/2022062309/56649f175503460f94c2d342/html5/thumbnails/20.jpg)
Homogenous Catalysts• Chlorofluorocarbons catalyze the decomposition of ozone.• Enzymes regulating the body processes. (Protein
catalysts)
![Page 21: TOPIC D: ARRHENIUS EQUATION AND CATALYSTS. Arrhenius Said the reaction rate should increase with temperature. At high temperature more molecules have](https://reader035.vdocuments.net/reader035/viewer/2022062309/56649f175503460f94c2d342/html5/thumbnails/21.jpg)
Catalysts and rate• Catalysts will speed up a reaction but only to a certain
point.• Past a certain point adding more reactants won’t change
the rate.• Zero Order
![Page 22: TOPIC D: ARRHENIUS EQUATION AND CATALYSTS. Arrhenius Said the reaction rate should increase with temperature. At high temperature more molecules have](https://reader035.vdocuments.net/reader035/viewer/2022062309/56649f175503460f94c2d342/html5/thumbnails/22.jpg)
Catalysts and rate.
• Rate increases until the active sites of catalyst are filled.
• Then rate is independent of concentration
Concentration of reactants
Rate