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Chemistry in Action
Key Terms
Synthesis
Decomposition
Polymerisation
Collision Theory
Kinetic Energy
Catalyst
Enzyme
Substrate
Active Site
Surface Area
Types of Chemical Reaction
Types of Chemical Reaction
Synthesis Using two products to create something new.
For example:
2H2 + O2 2H2O
Types of Chemical Reaction
Types of Chemical Reaction
Decomposition A substance is broken down to simpler products.
For example:
CaCO3 CaO + CO2
OR
2H2O 2H2 + O2
Types of Chemical Reaction
Types of Chemical Reaction
Types of Chemical Reaction
Polymerisation
A large number of monomers (single parts) are joined together to form a long chain called a polymer (many parts).
High density polymers have little branching.
Low density polymers have a lot of branching.
Reaction Rates
Controlling Reaction Rates
There are a number of things we can do to control the rate of a reaction.
When designing a process chemists need to consider: Should the reaction go quickly or slowly?
What would be the costs involved in controlling the reaction rate?
Are there any safety or environmental concerns?
More particles colliding leads to more reactions.
Collision Theory
Collision Theory
The particles must have the correct orientation.
Collision Theory
Collision Theory
The particles must have enough energy to bring about a reaction.
Collision Theory
Increasing Reaction Rate
Increased temperature Leads to increased frequency of collisions
Particles have greater kinetic energy
Increasing Reaction Rates
Increasing Reaction Rates
Increasing concentration of reactants. Leads to increased frequency of collisions
NOTE: Increasing the pressure of a gas is equivalent to increasing concentration of reactants.
Increasing Reaction Rates
Use of catalysts. Lowers the activation energy.
NOTE: Catalysts do not change during the reaction. They only facilitate it.
Increasing Reaction Rates
Haaaaave you met Ted?
Increasing Reaction Rates
Increasing Reaction Rate
Enzymes A special category of biological
catalysts.
They are proteins so they only work in certain pH and temperature ranges.
Enzymes are very specific and only work on a small range of substances.
Increasing Reaction Rates
Increasing Reaction Rates
The lock and key model. Substrate attaches to the active site on the enzyme.
Enzyme causes a reaction to occur.
Increasing Reaction Rates
Increasing surface area Allows for more collisions between particles.
Stirring is a way of increasing the surface area.
Increasing Reaction Rates
Image Credits
‘States of Matter’ by Wendy Adams et al available at https://phet.colorado.edu/en/simulation/states-of-matter courtesy of PhET Interactive Simulations at the University of Colorado.
‘Induced Fit Diagram’ By Created by TimVickers, vectorized by Fvasconcellos (Provided by TimVickers) available at http://upload.wikimedia.org/wikipedia/commons/2/24/Induced_fit_diagram.svg, via Wikimedia Commons
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