Chapter 15

Question 1

Rate of a chemical reaction

Answer 1

how fast the reaction occurs

Question 2

rate =

Answer 2

change in the amounts of reactants or products/ change in time

Question 3

Rate for reactants is (+ or -) because …

Answer 3

negative becuase they decrease as the reaction continues

Question 4

Rate for products is (+ or -) because …

Answer 4

postive becasue they increase as the reaction continues

Question 5

Find the rate of:
aA + bB -> cC +dD

Answer 5

-1/a (delta [A]/delta t) = -1/b (delta [B]/delta t) = +1/c (delta [C]/delta t) = +1/d (delta [D]/delta t)

Question 6

Rate law for zero order and list all of the factors of it

Answer 6

k[A]0 = k
- units M/s
- independent of the concentration of A
- concentration of reactant decreases linearly with time
- slope of a line is constant because the rate does not slow does as the concentration of A decreases
- rate of the reaction is the same at any concentration

Question 7

Rate law for first order and list all of the factors of it

Answer 7

k[A]1
-units: 1/s
-rate is directly proportional to the concentration of A
- rate slows down as reaction proceeds because concentration of reactants decreases

Question 8

Rate law for second order and list all of the factors of it

Answer 8

k[A]2
- units 1/M s
- rate is proportional to the square of the concentration
- curve flattens out more quickly

Question 9

initial rate

Answer 9

the rate for a short period of time at the beginning of the reaction
- its directly proportional to the initial concentration

Question 10

integrated rate law

Answer 10

a relationship between the concentration of the reactants and time

Question 11

first order integrated rate law

Answer 11

ln[A]t = -kt + ln[A]0

Question 12

Second order integrated rate law

Answer 12

1/[A]t = kt + 1/[A]0

Question 13

Zero order integrated rate law

Answer 13

[A]t = -kt + [A]0

Question 14

half life (t 1/2)

Answer 14

the time required for the concentration of a reactant to fall to one half of its initial value

Question 15

first order reaction half life

Answer 15

t 1/2 = ln 1/2 / k

Question 16

second order reaction half life

Answer 16

t 1/2 = 1/k[A]0

Question 17

zero order reaction half life

Answer 17

t 1/2 = [A]0/ 2k

Question 18

Activation Energy (Ea)

Answer 18

an energy barrier or hump that must be surmounted in order for the reactants to transform into products

Question 19

Frequency factor (A)

Answer 19

the number of times that the reactants approach the activation barrier per unit time

Question 20

higher the activation energy

Answer 20

slower the reaction rate

Question 21

reactant molecules

Answer 21

must collide in a specific way that allows for necessary bonds to break and form

Question 22

reaction mechanisms

Answer 22

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

Question 23

reaction intermediate

Answer 23

went from product to reactant

Question 24

finding k and what is its unit

Answer 24

rate/ [A]
unit: 1/s

Question 25

finding n

Answer 25

rate 2/ rate 1 = k[A]n/ k[A]n *log both sides

Question 26

from: aA + bB -> cC +dD
find the overall order

Answer 26

rate =k [A]m [B]n
m+n= overall order

Question 27

Graph for integrated first order

Answer 27

y axis: ln[A]t
x axis: time
slope: k

Question 28

graph for integrated second order

Answer 28

y axis: 1/[A]t
x axis: time
slope: k

Question 29

graph for integrated zero order

Answer 29

y axis: [A]t
x axis: time
slope: -k

Question 30

Calculating activation energy

Answer 30

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

Question 31

catalyst

Answer 31

went from reactant to product