Rates Flashcards
(Graphs) The graph of a zero order reaction plots ___ on the y-axis and ____ on the x-axis.
[A], time
(Graphs) The graph of a first order reaction plots ______ on the y-axis and ____ on the x-axis.
ln[A]t, time
“t” is a subscript
(Graphs) The graph of a second order reaction plots ______ on the y-axis and ____ on the x-axis.
1/[A]t, time
“t” is a subscript
(Misc.) Expression for Units of K
[M^(1-overall order)]/(unit time)
(Misc.) Expression for Overall Order
m+n (sum of all orders)
(Trends) As temperature increases, k (the rate constant)…
increases.
(Trends) As k (the reaction constant) increases, the reaction rate…
increases.
(Misc.) What do catalysts do?
Increase the rate of a reaction by participating in the formation of a new intermediate with a lower activation energy.
TL;DR: lower activation energy and increase reaction rate.
(Misc.) Are catalysts consumed or produced in a reaction?
No. If a compound is in a reaction, but not consumed or produced, it is a catalyst.
(Misc.) Factors affecting Reaction Rate
- RATE OF COLLISIONS between reactants.
- ORIENTATION of reactants colliding.
- ACTIVATION ENERGY of reactants colliding (Ec > Ea).
Ec = Collision Energy Ea = Activation Energy
(Trends) Collisions
Higher Temp. = More Collisions
Higher Temp. = More “Effective” Collisions (collisions with enough energy to cause a reaction)
Higher [R] = More Collisions
Greater Surface Area (Solid) = More Collisions
(Graphs) The graph of the Arrhenius Equation plots _____ on the y-axis and ___ on the x-axis.
ln(k), 1/T
k — rate constant
T — absolute temperature (Kelvin)
(Misc.) Finding Ea from Arrhenius Equation Graph
Step 1. Calculate the slope (m) of the line.
Step 2. Solve: m = -Ea/R
Ea = Activation Energy R = 8.314 J/mol*K
(Misc.) Reaction Intermediate
A substance that is produced and then consumed during the overall reaction.
(Misc.) Order and Elementary Steps
For any ELEMENTARY STEP (NOT overall balanced equation)…
aA + bB ➝ dD + eE
The rate law for that step is…
rate = k[A]ᵃ[B]ᵇ
