AP Chemistry Chapter 11 - Kinetics

Zero order reaction

A chemical reaction in which the rate remains constant as the concentration of the reactants rises or falls.

First order reaction

A chemical reaction in which the reaction rate is linearly dependent on the concentration of only one reactant.

Second order reaction

One whose rate is proportional to the square of the concentration of one reactant.

Half-life

The amount of time it takes for an initial concentration to drop to half of its original value.

Activation energy

The minimum amount of extra energy required by a reacting molecule to get converted into a product.

Reaction mechanism

The sequence of elementary steps by which a reaction occurs.

Unimolecular

Only one reactant molecule is necessary for the reaction to occur.

Bimolecular

Two reactant molecules must collide for the reaction to occur.

Termolecular

Three reactant molecules must collide for the reaction to occur.

Reactive intermediate

A substance that is formed in one step of a mechanism and then used up in a later step.

Rate-determining step

The slowest step of a reaction that determines the speed at which the overall reaction occurs. This step CANNOT have an intermediate as a reactant.

Enzyme

A biological catalyst.

what is the equation for average rates of reaction in kinetics

rate= -1/a Δ[A]/ ΔT….. reactants at -, products are +

---

5 factors affecting reactant rates

1. chemical nature of reactants

2. surface area of reactants

3. temperature

4. concentration of reactants

5. presence of a catalyst

k and m need to be deduced from _____________ data

experimental

k is dependent on

1. nature of reaction

2. Temperature

K is independent of

concentration

zero order is ____________ of concentration

independent

in first order, rates are ___________ to concentration

porportional

in second order, rates are ___________ concentration

porportional to the square of the concentration

to find overall order

sum of m and n

if half lives decrease with time _____ order

zero-order

if half lives are constant ______ order

first order

if half lives get longer

second order

Higher activation energy means faster or slower reaction?

slower

which step controls the reaction in an elementary reaction

the slowest

what order is this

zero order

what order is this

first order

what order is this

second

variable that changes half life

starting molarity

what is p

steric factor

is p temperature independent or dependent

independent

what is z

collision frequency

is collision frequency temperature independent or dependent

relatively temperature independent

why does temp affect reaction rates

as temp increases, more collision have sufficient energy to achieve Ea

every 10 degrees what happens to the reaction rate

doubles!

does the slowest step in a mechanism the lowest or highest activation energy

highest

what does a catalyst do

offers a second path of lower energy

what kind of catalysis is in different phases

heterogenious

what kind of catalysis is dispersed in a single phase, ususally liquid

homogeneous

what kind of catalysis are acid and base catalysis

homogeneous

what happens to the rate of a 0 order reaction over time

it stays constant

what happens to the rate of a 1st order reaction over time

it decreases

what happens to the rate of a 2nd order reaction over time

it decrease

what are the units of K for a second order reaction

mol²/L²-time

what is the unit for k in a first order reaction

time^-1

in a second order reaction what happens if more reactant is added

k and rate increase

what is the activation energy of the forward reaction

8 Kj

what is the delta h for the reaction

360 kJ

What is the activation energy for the reverse reaction

368 kJ

what is an species at point C called

activated complex