Chapter 5-Chemical Kinetics Flashcards
Positive versus negative Gibbs free energy
Positive signifies a nonspontaneous reaction.
Negative Gibbs free energy signifies a spontaneous reaction.
Intermediates
Molecules that exist within the course of a reaction but are neither reactants and products overall
What is the slowest step of a reaction that limits the maximum rate at which a reaction can proceed?
Rate determining step
Collision theory
States that her reaction rate is proportional to the number of effective collisions between the reacting molecules.
Arrhenius equation
What two things must occur in order for a reaction to exceed the activation energy?
Molecules must be in the proper orientation.
Molecules must have sufficient kinetic energy.
Transition state theory
Molecules form a transition state or activated complex during a reaction in which old bonds are partially dissociated and new bonds are partially formed.
Which part of the reaction is the highest point on a free energy reaction diagram?
The transition state
In what different ways can you impact reaction rates?
1) Increasing the concentration of a reactant. (Increases reaction rate except for zero order rxns)
2) Increasing the temperature of a reaction. (Increases reaction rate because the kinetic energy is increased)
3) Changing a medium can increase or decrease reaction rate depending how the reactants interact with the medium
4) Adding a catalyst increases reaction rate lowers activation energy.
Homogeneous catalyst versus heterogeneous catalyst
Homogeneous catalyst are the same phase as the reactants. Heterogeneous catalyst are in a different phase than the reactants.
How are rate laws determined?
Rate laws must be determined by experimental data.
Zero order reaction
How is it determined?
Have a constant rate that does NOT depend on the concentration of the reactant.
Can only be affected by changing the temperature adding a catalyst.
Concentration versus rate graph line is horizontal.
Slope -k
First order reactions
Have nonconstant rates that depends on the concentration of a reactant.
On a concentration versus rate graph line is diagonal
Slope -k
Second order reaction
Non-constant rate dependent on the concentration of reaction
concentration vs time curve: parabolic
slope=k
Mixed order reactions
Reactions with rate orders that either vary over the course of the reaction or have non-integer orders (fractions)
Broken order reactions
Reactions with rate orders that have non-integer orders (fractions)
