Unit 5: Kinetic Flashcards
The rate constant is depended on?
Temperature
Elementary reactions?
One that can occur in one step.
Maxwell-boltzmann distribution curve?
Labels the number of particles in a specific energy range (kinetic energy) depending on temperature. Area represents the probability of reacting.
Reaction coordinate?
Shows progress along the reaction time.
Energy profile?
Gives energy along reaction coordinate.
Arrhenius equation?
Relates temperature dependence of the rate of an elementary reaction to the activation energy needed by molecular collisions to reach the transition state.
When measuring reaction rate, you measure?
The rate of concentration
When measuring reaction rate, do you consider intermediates?
No
When determining rates of appearance and disappearance for each agent, what do you need to consider in order to set the rates of each agent to be equal?
Stoichiometry
Rate expression?
For the rate of each agent to be equal, the rate must be computed from the agent without a coefficient. This can be done using stochiometry.
Rate law?
Relationship between the rate and the concentration which are related by a proportionality constant, k.
Rate equation = ?
k[A]^m[B]^n, m & n are order of reaction.
How will different orders of a reaction change the rate if a double the concentration? 6•
•1st order m = 1: k[A], double concentration of A, rate will double
•2nd order m = 2: k[A]^2, double concentration of A, quadruple rate
•m = -1: k[A]^-1, double the concentration of A, half the rate
•m = -1/2: k[A]^-1/2, double the concentration of A, 0.7x the rate
•half order m = 1/2: k[A]^1/2, double the concentration of A, 1.4x the rate
•0 order m = 0: k, double the concentration of A, no change in the rate.
Overall rate order of a reaction is?
Sum of the exponents in the rate law.
Integrated rate law?
A rate function in terms of time.
With a first order integrated rate law, what can you do to simplify your work?
Reorder it into a linear equation.
Half life?
Time it takes for the original concentration to be reduced by half (t_1/2)
What does the half life depend on?
It depends on k, and k depends on the material in the question.
What reaction step is the slow and fast step?
The slow step is most similar to the order of the rate law of the total reaction.
Elementary reactions?
It involves at most two molecules
Why are elementary reactions important when analyzing reaction rates?
Because it is more unlikely for all reagents to collide simultaneously.
