13. Rate of Reaction and Collision Theory Flashcards
Define collision theory.
A theory accounting for chemical reaction rates in terms of the number of particle collisions in a reaction.
What 3 things must occur for a successful collision?
- Particles must collide with each other.
- Possess enough energy to break bonds
- Collide in the correct orientation
Define activation energy
The MINIMUM amount of energy needed for a chemical reaction to occur. It is denoted with E subscript a
What is enthalpy change?
Enthalpy change is the difference in energy between products and reactants (products - reactants)
What is the transition state?
When reactants receive activation energy, which is when the peak of the reaction diagram occurs.
Also known as the intermediate state.
In an energy profile diagram, do exothermic reactions have a higher or lower final energy?
Exothermic means loss of energy which means heats up surrounding system which means LOWER final energy.
In an energy profile diagram, do endothermic reactions have a higher or lower final energy?
Endothermic means absorbing energy from environment, means making surroundings colder therefore HIGHER final energy.
What is the formula for rate of reaction?
change in concentration/time
what are some factors that influence rate of reaction?
frequency of collisions
concentration of reactants
increasing energy of the system
increasing temperature
increasing pressure
increasing surface area
What type of curve shows the range of energies held by reactant particles?
A Maxwell-Boltzmann curve shows the range of energies held by reactant particles.
number of particles on y axis and kinetic energy on x axis
draw a vertical line to show a higher proportion of particles undergoing more successful collisions.
What is a catalyst?
A catalyst is a substance that provides a pathway of lower activation energy that does not affect the final outcome of a chemical reaction (not consumed in the process)
What is the difference between homogenous and heterogenous catalysts?
Homogenous catalysts are the same state as the reactants while heterogenous catalysts have DIFFERENT states from the reactants.
How do heterogenous catalysts work?
Heterogenous catalysts are in a different state from the other reactants (often solid) so that they are able to adsorb reactants (yes correct spelling) and reorientate them so that more successful collisions will occur.
Provide an example of a biological catalyst.
Enzymes are biological catalysts that catalyse important bodily reactions.
