Chapter 5-Chemical Kenetics Flashcards
Chemical mechanism
A proposed series of steps that make up the overall reaction.
Intermediate
Are molecules that exist within the course of a reaction but are neither reactants nor products.
Rate determining step
Slowest step in a chemical reaction. Limits the maximum rate at which a reaction can occur.
Reaction is only as fast as this step.
Collision theory
States that a reaction rate is proportional to the number of effective collisions btw the reacting molecules.
Effective collision
Orientation
Activation energy
Arrhenius equation
Mathematical representation of the collision theory.
Transition state theory
Molecules form a transition state/activated complex during a reaction in which new bonds form as old bonds break.
Graph of transition state
Highest peak.
From this state reaction can proceed forwards or backwards with no additional energy added.
Four factors that affect reaction rates.
1- increasing concentration (exception zero order reactions). Because more effective collisions per time.
2- increase temperature. Because increase KE of particles.
- Changing medium.
- Adding a catalyst.
Catalyst.
Speeds reaction but not consumed.
Homogeneous catalyst
Same phase as reactants.
Heterogeneous catalyst
Different phase as reactants.
Rate laws
Rate= k(A)^x(B)^y
Rate order
X +y
Zero Oder reactions
Affected only by changing temp or adding catalyst.
