chapter 14 (exam 2)

Question 1

integrated rate law for a chemical reaction is

Answer 1

relationship btw the concentrations of the reactants and time

Question 2

0th order integrated rate law

Answer 2

-the rate is proportional to a constant
[A]t = -kt + [A]0
[A]0 is the initial concentration of A

Question 3

1st order integrated rate law

Answer 3

-rate is directly proportional to the concentration of A
ln([A]t/[A]0)= -kt

Question 4

2nd order integrated rate law

Answer 4

-rate is proportional to the square of the concentration of A
(1/[A]t)= kt + (1/[A]0)

Question 5

half life

Answer 5

t1/2
the time required for the concentration of a reactant to fall to one-half of its initial value

Question 6

half life for first order

Answer 6

-half life is independent of the initial concentration of the reactant
t1/2 = (0.693)/k

Question 7

half life for zero order

Answer 7

-the lower the initial concentration of the reactants, the shorter the half life
t1/2 = [A]0/2k

Question 8

second order and half life

Answer 8

-inversely proportional to the initial concentration, increasing the initial concentration shortens the half life
t1/2 = 1/k[A]0

Question 9

collision theory

Answer 9

1) reactants (atoms, molecules, ions) must collide in an orientated way when the collide
2) molecules must have adequate kinetic energy to react (KE supplied must be enough to break the chemical bonds)

Question 10

activation energy

Answer 10

-the KE required to break the chemical bonds

Question 11

factors affecting number of collsions

Answer 11

1) the number of collisions is dependent on the number of gas particles in the system
2) increasing the amount of reactants, increases the total number of collisions

Question 12

increasing temperature causes molecules to

Answer 12

move faster resulting in more collisions and a higher rate of reaction

Question 13

temperature is a measure of the ___ and higher temp means ___

Answer 13

-average KE of molecules
-higher KE

Question 14

the higher the temperature(Ea)

Answer 14

the larger the fraction of molecules with KE = to or greater than the activation energy (Ea)

Question 15

a larger fraction of collisions (Ea) leads to product formation resulting in

Answer 15

higher rate of reaction

Question 16

heat of reaction is (-)

Answer 16

exothermic

Question 17

heat of reaction is (+)

Answer 17

endothermic

Question 18

reactants –> products

Answer 18

forward

Question 19

reactants <— products

Answer 19

backwards or reverse

Question 20

Activation energy (Ea)

Answer 20

-the minimum energy necessary to form a product during collision btw reactants
-height of the hill btw reactants and products

Question 21

higher the activation energy

Answer 21

the slower the reaction rate

Question 22

transition state/activation complex

Answer 22

-to get from reactant to product, molecule must go through high energy intermediate state

Question 23

Arrhenius equation

Answer 23

ln (k2/k1) = -Ea/R (1/T1 - 1/T2)

Question 24

reaction mechanisms

Answer 24

the series of individual chemical steps by which an overall chemical reaction occurs

Question 25

elementary step

Answer 25

each step in a reaction mechanism

Question 26

reaction intermediate

Answer 26

forms in one elementary step and is consumed in another

Question 27

number of hills tells you...

Answer 27

how many steps in the reaction mechanism

Question 28

elementary steps are characterized by

Answer 28

molecularity

Question 29

molecularity

Answer 29

the number of reactant particles involved in an elementary step

Question 30

unimolecular

Answer 30

-one particle -single reactant species to produce one or more molecules of product A--->products rate=k[A]

Question 31

bimolecular

Answer 31

-two particles -collision and combination of two molecules or atoms to form an activated complex A+A-->products rate=k[A]^2 A+B-->products rate=k[A][B]

Question 32

termolecular

Answer 32

-three particles A+B+C-->products rate=k[A][B][C] A+A+B-->products rate=k[A]^2[B] A+A+A-->products rate=k[A]^3

Question 33

rate determining step

Answer 33

-an individual step in an overall chemical reaction that occurs SLOWER than the other steps in the mechanism -determines the rate law for the overall reaction

Question 34

the slowest step has the

Answer 34

largest activation energy

Question 35

reaction intermediates

Answer 35

-do not appear in the overall equation -not in the rate law

Question 36

intermediates start as a ___ and ends as a___

Answer 36

starts: product ends: reactant

Question 37

factors affecting the reaction rate

Answer 37

-temp -concentration -chemical nature of reactants -state of subdivision of the reactants -presence of a catalyst

Question 38

temp and reaction rates

Answer 38

-increasing temperature increases the reaction rate -rate constant (k) depends on temp

Question 39

concentration and reaction rate

Answer 39

-the greater the concentration of reactant molecules, the faster the reaction -increases the frequency of reactant molecule contact

Question 40

chemical nature of reactants

Answer 40

as you move down group 1, alkali metals react at a faster rate with water

Question 41

the state of subdivision of the reactants

Answer 41

-the rate of most reactions increase with increasing surface area contact btw reactants

Question 42

catalyst

Answer 42

-catalyst increases the rate of the chemical reaction by lowering the activation energy without it being consumed y the reaction -regenerated in the process

Question 43

homogeneous catalysts

Answer 43

catalyst exists in same phase or state as the reactants

Question 44

heterogeneous catalyst

Answer 44

catalyst exists in a different phase or state as the reactants

Question 45

biological catalyst

Answer 45

enzymes

Question 46

catalyst that speed up reactions

Answer 46

positive catalysts

Question 47

catalyst that slows down a reaction

Answer 47

negative catalysts

Question 48

catalyst start as a ___ and end as a ___

Answer 48

starts: reactant ends: product