Module 2: Chemical Kinetics Flashcards
Factors affecting the rate of reaction
Nature of reactants
Reactant concentrations
Temperature
Catalysts
How does nature of reactants affect the rate
Ions are fast
Large molecules are slow
Surface area large is fast
Dissolving increases
How do reactant concentrations affect the rate of reaction
More concentration is higher rate
Depends but like generally
How does temperature affect rate of reaction
Usually higher temp increases it
How do catalysts affect rate of reaction
Make it faster
What is the rate law
Mathematical expression that shows how the rate depends on concentrations
How do you determine the rate law of a reaction
Experimentally
0 order plot
A vs t with slope -k
1st order plot
ln(A) vs t
Slope -k
2nd order plot
1/A vs t
Slope +k
Define half life
Time it takes for concentration to decrease to 1/2 initial value
Half life related to order
0 - decreases by factor of 2 for each successive
1 - constant
2 - increases by factor of 2 for each successive
Units of k - 0 order
mol L- s-
Units of k - 1st order
s-
Units of k - 2nd order
mol- L s-
Define reaction mechanism
Sequence of elementary processes that shows how the reactants are converted into products
Define elementary process
Specific collision all event or molecular process
Can’t be broken up into anything smaller
Why don’t all collisions lead to a reaction
Alignment might not be right
Steady state approximation
Rate of producing ~ rate of consuming
What happens to k, k-, for/rev rate, Keq of T increased
All increase except Keq if exothermic
Define catalyst
Provides a new mechanism with lower activation energy
Always permitted in rate law expression
Appears in reactants of step 1
