ch. 15

Question 1

factors that affect reaction rate

Answer 1

1. properties of reactants and products
2. ability of reactants to contact each other
3. concentrations
4. temperature
5. catalysts

Question 1

how do properties of reactants and products affect reaction rate

Answer 1

acid/base, ppt reaction, etc

Question 2

how does conc. affect reatction rate

Answer 2

higher conc. = more collisions = faster rate
lower conc. = less collisions = slower rate

Question 3

how does temp affect reaction rate

Answer 3

higher temp = more collisions (faster cules with more energy) = faster rate –> more cules w suffiecient energy

lower temp = less collisions = less cules w sufficient energy to overcome Ea

Question 4

how do catalysts affect reaction rate

Answer 4

speed up reaction by offering an alternate pathway with a lower Ea

inhibitor slows down reactions

Question 5

rate law

Answer 5

rate = k[A]^n

Question 6

finding rate law

Answer 6

rate2/rate1 = conc2/conc1

Question 7

how to find order of reaction when the reactions are complicated

Answer 7

you can get a pseudo order

increase the concentration of everything but the species of interst

makes changes in conc of everything else negligible

Question 8

integrated rate law vs differential rate law

Answer 8

concentrations depend on time

Question 9

half life

Answer 9

time required for conc. to decrease by 1/2

Question 10

for first order, half-life time is

Answer 10

constant

Question 11

for second order half life time

Answer 11

becomes longer with time

Question 12

zero order

Answer 12

rate doesn’t depend on conc.

like first order, graph slope =-k

Question 13

for zereo order, half life time

Answer 13

becomes shorter over time

Question 14

enzyme reactions are what order

Answer 14

zero order

Question 15

if a reaction is 2nd order, what graph axes will yield a linear plot

Answer 15

1/[A] vs. time

Question 16

collision theory

Answer 16

rate of reaction is proportional to the # of effective collisions

effective collisions consist of 2 thngs
1. enough energy
2. proper orientation

Question 17

exothermic energy diagrams –> describe

Answer 17

delta H = -
heat released
reactants higher than products

for reverse reaction Ea, Ea = delta H + Ea forwards rxn

Question 18

endothermic energy diagram

Answer 18

heat absorbed
delta H = +
reactants less than products

Question 19

what does the top of a energy diagram symbolize

Answer 19

transition state

high energy + unstable

Question 20

arrhenius equation

k = Ae^(-Ea/RT)

describe the variables

Answer 20

k = rate constant

A = frequency factor

Ea = activation enrgy

R = 8.3145

T = K

Question 21

mechanisms

Answer 21

most reactions don’t occur in a single step

mechanism is a series of elementary steps

sum of elementary steps gives overall reaction

mechanism agrees w rate law

Question 22

first order reaction can also be called
second order
third order

Answer 22

unimolecular

bimolecular

termolecular

Question 23

what step of a mechanism is used to construct the rate law

Answer 23

slow step