General Chemistry Chapter 5: Chemical Kinetics Flashcards
What is the Gibbs free energy?
determines whether or not a reaction is spontaneous
Intermediates
molecules that exist within the course of a reaction, but are neither reactants nor products overall.
What is the slowest step?
Rate-determining step - limits the maximum rate at which the reaction can proceed.
What is the collision theory?
A reaction rate is proportional to the number of effective collisions between the reacting molecules
- proper orientation
- sufficient kinetic energy to exceed Ea
What is the Arrhenius equation?
A mathematical way of representing collision theory
What is the transition state theory?
states that molecules form a transition state or activated complex during a reaction in which the old bonds are partially dissociated and the new bonds are partially formed.
What is the highest point of free energy in a reaction?
The transition state
What can affect the reaction rate?
- Increasing the concentration of reactant = increase r.r. because more collisions
- Increasing the temperature = increase r.r. because more kinetic energy
- changing the medium
- adding a catalyst = increase r.r.
Homogeneous catalyst
same phase as the reactants
Heterogeneous catalyst
different phase
How are rate orders determined?
Must be determined via experimental data - generally do not match the stoichiometric coefficients
What is the rate order?
the sum of all individual rate orders in the late law
What are zero-order reactions?
Have a constant rate that does not depend on the concentration
- Can only be affected by changing temp or adding a catalyst
- curve = straight line w/ a slope -k
What are first-order reactions?
Have a non-constant rate that depends on the concentration of reactant.
- Non-linear
- Slope of a ln [A] v. time is -k
What is a second-order reaction?
have a nonconstant rate that depends on the concentration
- Non-linear
Slope of 1/[A] is k
