Exam 2

Question 1

Delta S (universe) > 0; Delta G < 0

Answer 1

Process is spontaneous as written

Question 2

Delta S (universe) = 0; Delta G = 0

Answer 2

Reversible (process is not spontaneous in either direction) - system is at equilibrium

Question 3

Delta S (universe) < 0; Delta G > 0

Answer 3

Process is spontaneous in reverse direction

Question 4

Delta H = (-); Delta S = (-); -T Delta S = (+)

Answer 4

Spontaneous at low temp

Question 5

Delta H = (+); Delta S = (+); -T Delta S = (-)

Answer 5

Spontaneous at high temp

Question 6

What is physically happening to make Delta S&raquo_space;> 0?

Answer 6

Formation of ions, ion-solvent interactions, increased disorder

Question 7

What is physically happening to make Delta H&raquo_space;> 0?

Answer 7

Absorbing heat in the dissolution process

Question 8

If Delta G = 0, what equation can you use?

Answer 8

0 = Delta S (system) - T Delta S (system)

Question 9

Rate of disappearance and rate of appearance

Answer 9

stoichiometric value of reactant / stoichiometric value of product = disappearance of reaction is ____ the appearance of product

Question 10

Information we can get from kinetics

Answer 10

Speed, factors that influence speed; molecular mechanism (how the reaction occurs)

Question 11

How do chemicals react?

Answer 11

must collide with enough energy and in the correct orientation

Question 12

The more homogeneous the mixture of reactants

Answer 12

the faster the molecules can react

Question 13

As the concentration of reactants increases

Answer 13

the likelihood that reactant molecules will collide increases

Question 14

Catalyst

Answer 14

speed up reactions by changing the mechanism of the reaction; not consumed during the course of the overall reaction

Question 15

Rate law

Answer 15

Rate = k[A]^n[B]^m ; n = reaction order of A; m = reaction order of B; overall reaction order = n + m

Question 16

Determining Rate laws using Initial rates (change the concentration of only one of the reactants)

Answer 16

Rate 2/Rate 1 = k[B2]^n [C2]^m / k[B1]^n [C1]^m

Question 17

Zero Order Equations

Answer 17

[At] = [Ao] -kt

Question 18

Zero Order Graph

Answer 18

m = -k; y-intercept = [Ao], concentration as a function of time

Question 19

1st order Equations

Answer 19

ln [At]/[Ao] = -kt ; [At] = [Ao]e^-kt

Question 20

2nd order Equations

Answer 20

1/[At] - 1/[Ao] = kt; 1/[At] = kt + 1/[Ao]

Question 21

Zero Order Equations

Answer 21

0.5[Ao] /k = t1/2

Question 22

1st order Equations

Answer 22

ln2/k = t1/2

Question 23

2nd order Equations

Answer 23

1/k[Ao] = t1/2

Question 24

Transition State

Answer 24

The (rare) arrangement of atoms at the energy maximum during the course of the reaction

Question 25

Activation Energy

Answer 25

the energy required to overcome the reaction barrier

Question 26

k = Ae^(-Ea/RT)

Answer 26

A is the frequency factor, Ea is the activation energy, T is the absolute temperature

Question 27

Intermediates are written

Answer 27

written below the line at each step

Question 28

Transition states are written

Answer 28

above the line

Question 29

the number of steps in the mechanism is indicated by

Answer 29

counted based on the bottom of each “hill”

Question 30

A catalyst influence the rate of a reaction by altering

Answer 30

the value of Ea

Question 31

A catalyst does not alter

Answer 31

the delta E of a reaction

Question 32

catalysts are often prepared so they have ________ surface areas

Answer 32

very large

Question 33

the rate-determining step is

Answer 33

the slowest reaction

Question 34

unimolecular

Answer 34

only on reactant involved; A —> products

Question 35

Bimolecular

Answer 35

two molecules must collide to produce products; A + B ——> Products; 2A —–> Products

Question 36

Termolecular

Answer 36

three different molecules must collide; A + B + C —-> Products; A + 2B —–> Products; 3A ——> Products

Question 37

Exothermic reaction graph

Answer 37

reactants are higher than the products

Question 38

Endothermic reaction graph

Answer 38

reactants are lower than the products

Question 39

Homogenous Catalyst

Answer 39

has the same phase as the molecules in the reaction

Question 40

Heterogenous Catalyst

Answer 40

has a different phase than the molecules in the reaction

Question 41

Equilibrium is a state of dynamic molecular behavior, meaning that

Answer 41

reactants turn into products and products turn into reactants at equal rates

Question 42

Equilibrium can only be achieved in a ______ system

Answer 42

closed system

Question 43

Kf/Kr = keq

Answer 43

forward and reverse reactions

Question 44

Equilibirum constant expressions

Answer 44

product/reactants; only gas and aqueous

Question 45

Kc«< 1

Answer 45

Reactant Favored, reactant predominates at equilibrium

Question 46

Kc»>1

Answer 46

Product Favored, product predominates at equilibrium

Question 47

Qc has the same form as Keq

Answer 47

but there is no assumption of equilibrium

Question 48

Q<K

Answer 48

System has too much reactant; shift toward product

Question 49

Q=K

Answer 49

System is at equilibrium

Question 50

Q>K

Answer 50

System has too much product; shift toward reaction