Unit 5 Flashcards
Reaction rate
the speed of a reaction - which can CHANGE over time
k
rates are always…
positive
Average rate equation
Δ[A] / Δt (A = products)
- Δ[B] / Δt (B = reactants)
Instanteneous Rate
rate for a specific interval of time
Reaction order
the sensetivity of M of the reactants to the rate
Higher reaction order means…
higher sensitivity to changes of molarity
What is the average rate for
2B = C
- 1/2 Δ[B] / Δt
How are exponents figured out in rate reactions?
Experimental data, NOT stochiometric data
How is the rate described?
it is measured by
1. disappearance of reactants
2. appearance of products
What are the four factors for reaction rates?
- M
- Surface Area
- Temperature
- Catalyst
Rate of zero order reaction
rate = k
Rate of first order reaction
rate = k[A]
Rate of second order reacton
rate = k[A]^2
What does the unit for rate always have to be?
M/t
zero order reaction half life
[A]_0 / 2k
first order reaction half life
0.693 / k
second order reaction half life
1 / k [A]_0
Integrated Rate Law (IRL) does what?
determines M at a given point
IRL of zero order
[A]_t = -kt + [A]_0
IRL of first order
ln [A]_t = -kt + ln [A]_0
IRL of second order
1/ [A]_t = kt + 1/[A]_0
If stochiometric coeficcient is a, than the IRL is.. (first order)
ln [A]_t = - (1/a)kt + ln [A]_0
Radioactive Decay
Process by which an unstable atomic nucleus loses energy by emitting energy - isotopes
What are the three radioactive decay particles/waves
alpha particles
beta particles
gamma rays
What law does radioactive decay follow?
First Order Rate Law
elementary reaction
breaking down of the reaction into its steps
unimolecular reaction
a reaction with one reactent
bimolecular
two reactants in the reaction
Rate determining step is….
the slow reaction
the intermediate step
a substance which is BOTH made and consumed
Pre-equilibrium approximation
in the fast elementary step, we can assume the reverse reaction
What are the three requirements for the collision theory?
- they must collide
- correct orientation
- enough energy to get over activation energy
catalyst
increase the rate at which reactants are consumed by lowering the Activation Energy
What are three examples of catalyst?
- enzyme
- homogeneous catalyst
- heterogeneous catalyst
Rule of thumb is, if the Temperature is increased 10 degrees C/K, the reaction rate…
doubles
Activated Complex
at the peak of the hump, partial reactant and partial product bonds
