This document provides an overview of catalysis for A-level chemistry students. It begins with background information on enthalpy changes and activation energy in chemical reactions. It then discusses the principles of heterogeneous and homogeneous catalysis, including how catalysts lower the activation energy of reactions by providing alternative reaction pathways. Specific examples discussed include catalytic converters used to reduce automobile emissions. The document also covers concepts such as catalytic specificity, poisoning of catalysts, and auto-catalysis involving transition metal compounds.
THE PERICYCLIC REACTION THE MOST COMMON TOPIC INCLUDE THE SYLLABUS OF MANY SCIENCE STUDY INCLUDING BSC, MSC , PHARMA STUDY, AND MORE HENCE WE ARE COVERED ALL THE DATA OF IT HOPE THIS WILL MAKE READER EASY.
This powerpoint presentation will cover following aspects:
Kinds of Pericyclic Reactions and Brief details of their kinds
Molecular Orbitals and Orbitals Symmetry
Molecular Orbitals Description
Electrocyclic Reactions
Introduction to Dienes
Introduction to Dienophiles
Photochemical conditions
Ring Closure
Modes of Ring Closure
Diels- Alder Product recognition and Reversibility of Diels Alder Reaction
Conrotatory and Disrotatory arrangements
Cycloadditions in Complete Details
Dimerization , Frontier Orbitals Description, Endo Rule, Stereochemistry, Applications Hoffman's rule and a lot more……
Introduction
Basis
Importance
Classification
Homogeneous catalysis
Mechanism
Example
Heterogeneous catalysis
Mechanism
Examples
Promoters
Catalytic Poisoning
Autocatalysis
Enzyme catalysis
Enzymes
References
Catalyst: -
The substances that alter the rate of a reaction but itself remains chemically unchanged at the end of the reaction is called a Catalyst.
The process is called Catalysis.
prop-
A catalyst cannot start the reaction by itself.
Catalytic activity increases as surface area of catalyst increases.
Catalysts are thermolabile, this effect is very well pronounced in enzymes.
Catalytic activity is maximum at a catalyst’s optimum temperature.
A catalyst does not alter the position of the equilibrium, instead it helps in achieving the equilibrium faster.
Catalysis Science & Technology covers both the science of catalysis and catalysis technology, including applications addressing global issues. The journal publishes research in the applied, fundamental, experimental and computational areas of catalysis. Contributions are made by the homogeneous, heterogeneous and biocatalysis communities.
THE PERICYCLIC REACTION THE MOST COMMON TOPIC INCLUDE THE SYLLABUS OF MANY SCIENCE STUDY INCLUDING BSC, MSC , PHARMA STUDY, AND MORE HENCE WE ARE COVERED ALL THE DATA OF IT HOPE THIS WILL MAKE READER EASY.
This powerpoint presentation will cover following aspects:
Kinds of Pericyclic Reactions and Brief details of their kinds
Molecular Orbitals and Orbitals Symmetry
Molecular Orbitals Description
Electrocyclic Reactions
Introduction to Dienes
Introduction to Dienophiles
Photochemical conditions
Ring Closure
Modes of Ring Closure
Diels- Alder Product recognition and Reversibility of Diels Alder Reaction
Conrotatory and Disrotatory arrangements
Cycloadditions in Complete Details
Dimerization , Frontier Orbitals Description, Endo Rule, Stereochemistry, Applications Hoffman's rule and a lot more……
Introduction
Basis
Importance
Classification
Homogeneous catalysis
Mechanism
Example
Heterogeneous catalysis
Mechanism
Examples
Promoters
Catalytic Poisoning
Autocatalysis
Enzyme catalysis
Enzymes
References
Catalyst: -
The substances that alter the rate of a reaction but itself remains chemically unchanged at the end of the reaction is called a Catalyst.
The process is called Catalysis.
prop-
A catalyst cannot start the reaction by itself.
Catalytic activity increases as surface area of catalyst increases.
Catalysts are thermolabile, this effect is very well pronounced in enzymes.
Catalytic activity is maximum at a catalyst’s optimum temperature.
A catalyst does not alter the position of the equilibrium, instead it helps in achieving the equilibrium faster.
Catalysis Science & Technology covers both the science of catalysis and catalysis technology, including applications addressing global issues. The journal publishes research in the applied, fundamental, experimental and computational areas of catalysis. Contributions are made by the homogeneous, heterogeneous and biocatalysis communities.
This ppt includes overall idea of what is enzymes, how it works, mechanism of enzymes, kinetics and how to inhibit enzyme activities. The reference is the ideal book for biochemistry - Lehninger . Understanding is easy for everyone.
Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)MdTanvirMahtab2
This presentation is about the working procedure of Shahjalal Fertilizer Company Limited (SFCL). A Govt. owned Company of Bangladesh Chemical Industries Corporation under Ministry of Industries.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
About
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
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• Remote control system for accessing CCR and allied system over serial or TCP.
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Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
2. CATALYSISCATALYSIS
INTRODUCTION
This Powerpoint show is one of several produced to help students understand
selected topics at AS and A2 level Chemistry. It is based on the requirements of
the AQA and OCR specifications but is suitable for other examination boards.
Individual students may use the material at home for revision purposes or it
may be used for classroom teaching if an interactive white board is available.
Accompanying notes on this, and the full range of AS and A2 topics, are
available from the KNOCKHARDY SCIENCE WEBSITE at...
www.argonet.co.uk/users/hoptonj/sci.htm
Navigation is achieved by...
either clicking on the grey arrows at the foot of each page
or using the left and right arrow keys on the keyboard
KNOCKHARDY PUBLISHINGKNOCKHARDY PUBLISHING
4. Before you start it would be helpful to…
• know how the basics of collision theory
• understand the importance of activation energy
• understand the importance of increasing the rate of reaction
CATALYSISCATALYSIS
5. CATALYSTS - backgroundCATALYSTS - background
All reactions are accompanied by changes in enthalpy.
The enthalpy rises as the reaction starts because energy is being put in to break bonds.
It reaches a maximum then starts to fall as bonds are formed and energy is released.
ENTHALPY CHANGE DURING
AN EXOTHERMIC REACTION
6. CATALYSTS - backgroundCATALYSTS - background
All reactions are accompanied by changes in enthalpy.
The enthalpy rises as the reaction starts because energy is being put in to break bonds.
It reaches a maximum then starts to fall as bonds are formed and energy is released.
ENTHALPY CHANGE DURING
AN EXOTHERMIC REACTION
If the…
FINAL ENTHALPY < INITIAL ENTHALPY
it is an EXOTHERMIC REACTION
and ENERGY IS GIVEN OUT
7. CATALYSTS - backgroundCATALYSTS - background
All reactions are accompanied by changes in enthalpy.
The enthalpy rises as the reaction starts because energy is being put in to break bonds.
It reaches a maximum then starts to fall as bonds are formed and energy is released.
ENTHALPY CHANGE DURING
AN EXOTHERMIC REACTION
If the…
FINAL ENTHALPY < INITIAL ENTHALPY
it is an EXOTHERMIC REACTION
and ENERGY IS GIVEN OUT
FINAL ENTHALPY > INITIAL ENTHALPY
it is an ENDOTHERMIC REACTION
and ENERGY IS TAKEN IN
8. CATALYSTS - backgroundCATALYSTS - background
ACTIVATION ENERGY - Ea
• Reactants will only be able to proceed to products if they have enough energy
• The energy is required to overcome an energy barrier
• Only those reactants with enough energy will get over
• The minimum energy required is known as the ACTIVATION ENERGY
ACTIVATION ENERGY Ea FOR
AN EXOTHERMIC REACTION
9. CATALYSTS - backgroundCATALYSTS - background
COLLISION THEORYCOLLISION THEORY
According to COLLISON THEORY a reaction will only take place if…
• PARTICLES COLLIDE
• PARTICLES HAVE AT LEAST A MINIMUM AMOUNT OF ENERGY
• PARTICLES ARE LINED UP CORRECTLY
To increase the chances of a successful reaction you need to...
• HAVE MORE FREQUENT COLLISONS
• GIVE PARTICLES MORE ENERGY or
• DECREASE THE MINIMUM ENERGY REQUIRED
10. NUMBEROFMOLECUESWITH
APARTICULARENERGY
MOLECULAR ENERGY Ea
DUE TO THE MANY COLLISONS
TAKING PLACE IN GASES, THERE
IS A SPREAD OF MOLECULAR
ENERGY AND VELOCITY
DUE TO THE MANY COLLISONS
TAKING PLACE IN GASES, THERE
IS A SPREAD OF MOLECULAR
ENERGY AND VELOCITY
NUMBER OF
MOLECULES WITH
SUFFICIENT ENERGY
TO OVERCOME THE
ENERGY BARRIER
MAXWELL-BOLTZMANN DISTRIBUTIONMAXWELL-BOLTZMANN DISTRIBUTION
The area under the curve beyond Ea corresponds to the number of molecules with
sufficient energy to overcome the energy barrier and react.
If a catalyst is added, the Activation Energy is lowered - Ea will move to the left.
11. The area under the curve beyond Ea corresponds to the number of molecules with
sufficient energy to overcome the energy barrier and react.
Lowering the Activation Energy, Ea, results in a greater area under the curve after Ea
showing that more molecules have energies in excess of the Activation Energy
Ea
EXTRA NUMBER OF
MOLECULES WITH
SUFFICIENT ENERGY
TO OVERCOME THE
ENERGY BARRIER
MAXWELL-BOLTZMANN DISTRIBUTIONMAXWELL-BOLTZMANN DISTRIBUTION
NUMBEROFMOLECUESWITH
APARTICULARENERGY
MOLECULAR ENERGY
DUE TO THE MANY COLLISONS
TAKING PLACE IN GASES, THERE
IS A SPREAD OF MOLECULAR
ENERGY AND VELOCITY
DUE TO THE MANY COLLISONS
TAKING PLACE IN GASES, THERE
IS A SPREAD OF MOLECULAR
ENERGY AND VELOCITY
12. Catalysts work by providing…
“AN ALTERNATIVE REACTION PATHWAY WHICH HAS A LOWER ACTIVATION ENERGY”
CATALYSTS - lower ECATALYSTS - lower Eaa
A GREATER PROPORTION OF PARTICLES WILL HAVE ENERGIES
IN EXCESS OF THE MINIMUM REQUIRED SO MORE WILL REACT
WITHOUT A CATALYST WITH A CATALYST
13. PRINCIPLES OF CATALYTIC ACTIONPRINCIPLES OF CATALYTIC ACTION
The two basic types of catalytic action are …
HETEROGENEOUS CATALYSIS
and
HOMOGENEOUS CATALYSIS
14. Format Catalysts are in a different phase to the reactants
e.g. a solid catalyst in a gaseous reaction
Action takes place at active sites on the surface of a solid
gases are adsorbed onto the surface
they form weak bonds with metal atoms
Catalysis is thought to work in three stages...
AdsorptionAdsorption
ReactionReaction
DesorptionDesorption
Heterogeneous CatalysisHeterogeneous Catalysis
16. Heterogeneous CatalysisHeterogeneous Catalysis
Adsorption (STEP 1)
Incoming species lands on an active site and forms bonds with the catalyst. It may use some of the
bonding electrons in the molecules thus weakening them and making a subsequent reaction easier.
17. Heterogeneous CatalysisHeterogeneous Catalysis
Adsorption (STEP 1)
Incoming species lands on an active site and forms bonds with the catalyst. It may use some of the
bonding electrons in the molecules thus weakening them and making a subsequent reaction easier.
Reaction (STEPS 2 and 3)
Adsorbed gases may be held on the surface in just the right orientation for a reaction to occur.
This increases the chances of favourable collisions taking place.
18. Heterogeneous CatalysisHeterogeneous Catalysis
Desorption (STEP 4)
There is a re-arrangement of electrons and the products are then released from the active sites
Adsorption (STEP 1)
Incoming species lands on an active site and forms bonds with the catalyst. It may use some of the
bonding electrons in the molecules thus weakening them and making a subsequent reaction easier.
Reaction (STEPS 2 and 3)
Adsorbed gases may be held on the surface in just the right orientation for a reaction to occur.
This increases the chances of favourable collisions taking place.
19. ANIMATIONANIMATION
Heterogeneous CatalysisHeterogeneous Catalysis
Desorption (STEP 4)
There is a re-arrangement of electrons and the products are then released from the active sites
Adsorption (STEP 1)
Incoming species lands on an active site and forms bonds with the catalyst. It may use some of the
bonding electrons in the molecules thus weakening them and making a subsequent reaction easier.
Reaction (STEPS 2 and 3)
Adsorbed gases may be held on the surface in just the right orientation for a reaction to occur.
This increases the chances of favourable collisions taking place.
21. STRENGTH OF ADSORPTIONSTRENGTH OF ADSORPTION
The STRENGTH OF ADSORPTION is critical ...
too weak Ag little adsorption - few available d orbitals
too strong W molecules remain on the surface preventing further reaction
just right Ni/Pt molecules are held but not too strongly so they can get away
Catalysis of gaseous reactions can lead to an increase in rate in several ways
• one species is adsorbed onto the surface and is more likely to undergo a collision
• one species is held in a favourable position for reaction to occur
• adsorption onto the surface allows bonds to break and fragments react quicker
• two reactants are adsorbed alongside each other give a greater concentration
22. EXAMPLES OF CATALYSTSEXAMPLES OF CATALYSTS
Metals Ni, Pt hydrogenation reactions
Fe Haber Process
Rh, Pd catalytic converters
Oxides Al2O3 dehydration reactions
V2O5 Contact Process
Format FINELY DIVIDED increases the surface area
provides more collision sites
IN A SUPPORT MEDIUM maximises surface area and reduces costs
23. SpecificitySpecificity
In some cases the choice of catalyst can influence the products
C2H5OH ——> CH3CHO + H2 C2H5OH ——> C2H4 + H2O
Ethanol undergoes different reactions depending on the metal used as the catalyst.
The distance between active sites and their similarity with the length of bonds
determines the method of adsorption and affects which bonds are weakened.
Alumina DehydrationCopper Dehydrogenation (oxidation)
24. Ethanol undergoes two different reactions depending on the metal used as the catalyst.
COPPER Dehydrogenation (oxidation)
C2H5OH ——> CH3CHO + H2
The active sites are the same distance
apart as the length of an O-H bond
It breaks to release hydrogen
ALUMINA Dehydration (removal of water)
C2H5OH ——> C2H4 + H2O
The active sites are the same distance
apart as the length of a C-O bond
It breaks to release an OH group
SpecificitySpecificity
25. PoisoningPoisoning
Impurities in a reaction mixture can also adsorb onto the surface of a catalyst thus
removing potential sites for gas molecules and decreasing efficiency.
expensive because... the catalyst has to replaced
the process has to be shut down
examples Sulphur Haber process
Lead catalytic converters in cars
26. Catalytic convertersCatalytic converters
PURPOSE To remove pollutant gases formed in internal combustion engines
CONSTRUCTION made from alloys of platinum, rhodium and palladium
catalyst is mounted in a support medium to spread it out
honeycomb construction to ensure maximum gas contact
finely divided to increase surface area / get more collisions
involves HETEROGENEOUS CATALYSIS
POLLUTANTS CARBON MONOXIDE, NITROGEN OXIDES, UNBURNT HYDROCARBONS
27. Pollutant gasesPollutant gases
Carbon monoxide CO
Origin incomplete combustion of hydrocarbons in petrol because there wasn’t
enough oxygen present to convert all the carbon to carbon dioxide
C8H18(g) + 8½O2(g) ——> 8CO(g) + 9H2O(l)
Effect poisonous
combines with haemoglobin in blood
prevents oxygen being carried Oxidation of carbon monoxide
Removal 2CO(g) + O2(g) ——> 2CO2(g)
2CO(g) + 2NO(g) ——> N2(g) + 2CO2(g)
28. Pollutant gasesPollutant gases
Oxides of nitrogen NOx - NO, N2O and NO2
Origin nitrogen and oxygen combine under high temperature conditions
nitrogen combines with oxygen N2(g) + O2(g) ——> 2NO(g)
nitrogen monoxide is oxidised 2NO(g) + O2(g) ——> 2NO2(g)
Effect photochemical smog - irritating to eyes, nose and throat
produces low level ozone - affects plant growth
- is irritating to eyes, nose and throat
i) sunlight breaks down NO2 NO2 ——> NO + O
ii) ozone is produced O + O2 ——> O3
Removal 2CO(g) + 2NO(g) ——> N2(g) + 2CO2(g)
29. Pollutant gasesPollutant gases
Unburnt hydrocarbons CxHy
Origin hydrocarbons that have not undergone combustion due to insufficient oxygen
Effect toxic and carcinogenic (causes cancer)
Removal catalyst aids complete combustion
C8H18(g) + 12½O2(g) ——> 8CO2(g) + 9H2O(l)
30. Homogeneous CatalysisHomogeneous Catalysis
Action • catalyst and reactants are in the same phase
• reaction proceeds through an intermediate species with lower energy
• there is usually more than one reaction step
• transition metal ions are often involved - oxidation state changes
Example
Acids Esterificaton
Conc. sulphuric acid catalyses the reaction between acids and alcohols
CH3COOH + C2H5OH CH3COOC2H5 + H2O
NB Catalysts have NO EFFECT ON THE POSITION OF EQUILIBRIUM
but they do affect the rate at which equilibrium is reached
31. Homogeneous CatalysisHomogeneous Catalysis
Action • catalyst and reactants are in the same phase
• reaction proceeds through an intermediate species with lower energy
• there is usually more than one reaction step
• transition metal ions are often involved - oxidation state changes
32. Homogeneous CatalysisHomogeneous Catalysis
Action • catalyst and reactants are in the same phase
• reaction proceeds through an intermediate species with lower energy
• there is usually more than one reaction step
• transition metal ions are often involved - oxidation state changes
Examples
Gases Atmospheric OZONE breaks down naturally O3 ——> O• + O2
- it breaks down more easily in the presence of chlorofluorocarbons (CFC's).
There is a series of complex reactions but the basic process is :-
CFC's break down in the presence of
UV light to form chlorine radicals CCl2F2 ——> Cl• + • CClF2
chlorine radicals then react with ozone O3 + Cl• ——> ClO• + O2
chlorine radicals are regenerated ClO• + O ——> O2 + Cl•
Overall, chlorine radicals are not used up so a small amount of CFC's can
destroy thousands of ozone molecules before the termination stage.
33. Transition metal compoundsTransition metal compounds
These work because of their ability to change oxidation state
1. Reaction between iron(III) and vanadium(III)
The reaction is catalysed by Cu2+
step 1 Cu2+
+ V3+
——> Cu+
+ V4+
step 2 Fe3+
+ Cu+
——> Fe2+
+ Cu2+
overall Fe3+
+ V3+
——> Fe2+
+ V4+
1. Reaction between iron(III) and vanadium(III)
The reaction is catalysed by Cu2+
step 1 Cu2+
+ V3+
——> Cu+
+ V4+
step 2 Fe3+
+ Cu+
——> Fe2+
+ Cu2+
overall Fe3+
+ V3+
——> Fe2+
+ V4+
34. Transition metal compoundsTransition metal compounds
These work because of their ability to change oxidation state
2. Reaction between I¯ and S2O8
2-
A slow reaction because REACTANTS ARE NEGATIVE IONS ∴ REPULSION
Addition of iron(II) catalyses the reaction
step 1 S2O8
2-
+ 2Fe2+
——> 2SO4
2-
+ 2Fe3+
step 2 2Fe3+
+ 2I¯ ——> 2Fe2+
+ I2
overall S2O8
2-
+ 2I¯ ——> 2SO4
2-
+ I2
2. Reaction between I¯ and S2O8
2-
A slow reaction because REACTANTS ARE NEGATIVE IONS ∴ REPULSION
Addition of iron(II) catalyses the reaction
step 1 S2O8
2-
+ 2Fe2+
——> 2SO4
2-
+ 2Fe3+
step 2 2Fe3+
+ 2I¯ ——> 2Fe2+
+ I2
overall S2O8
2-
+ 2I¯ ——> 2SO4
2-
+ I2
35. Auto-catalysisAuto-catalysis
Occurs when a product of the reaction catalyses the reaction itself
It is found in the reactions of manganate(VII) with ethandioate
2MnO4¯ + 16H+
+ 5C2O4
2-
——> 2Mn2+
+ 8H2O + 10CO2
The titration needs to be carried out at 70°C because the reaction is slow as Mn2+
is
formed the reaction speeds up; the Mn2+
formed acts as the catalyst
36. Activity is affected by ...
temperature - it increases until the protein is denatured
substrate concentration - reaches a maximum when all sites are blocked
pH - many catalysts are amino acids which can be protonated
being poisoned - when the active sites become “clogged” with unwanted
ENZYMESENZYMES
ActionAction enzymes are extremely effective biologically active catalysts
they are homogeneous catalysts, reacting in solution with body fluids
only one type of molecule will fit the active site “lock and key” mechanism
makes enzymes very specific as to what they catalyse.
37. ENZYMESENZYMES
ActionAction enzymes are extremely effective biologically active catalysts
they are homogeneous catalysts, reacting in solution with body fluids
only one type of molecule will fit the active site “lock and key” mechanism
makes enzymes very specific as to what they catalyse.
AA BB CC
AA Only species with the correct shape can enter the active site in the enzyme
BB Once in position, the substrate can react with a lower activation energy
CC The new products do not have the correct shape to fit so the complex breaks up
38. ENZYMESENZYMES
ANIMATED ACTIONANIMATED ACTION
AA Only species with the correct shape can enter the active site in the enzyme
BB Once in position, the substrate can react with a lower activation energy
CC The new products do not have the correct shape to fit so the complex breaks up
39. REVISION CHECKREVISION CHECK
What should you be able to do?
Recall the definition of a catalyst
Explain qualitatively how a catalyst works
Understand the difference between homogeneous and heterogeneous catalysis
Explain how heterogeneous catalysts work
Understand the importance of active sites, poisoning and specificity
Recall and understand the importance of catalytic converters
Explain how homogeneous catalysts work
Work out possible steps in simple reactions involving homogeneous catalysis
Recall and understand how enzymes work
CAN YOU DO ALL OF THESE?CAN YOU DO ALL OF THESE? YESYES NONO
40. You need to go over theYou need to go over the
relevant topic(s) againrelevant topic(s) again
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