Chem 112 Exam 2

Question 1

When we double the quantities of reactants and products in a reaction, what happens to the value of the equilibrium constant?

Answer 1

The equilibrium constant is squared

Question 2

What is a homogenous equilibrium?

Answer 2

When all of the reactants and products are in the same phase

Question 3

What is the general form for the equilibrium constant?

Answer 3

Kc=[products]/[reactants]

Question 4

Does the equilibrium constant, Keq depend on temperature?

Answer 4

yes

Question 5

Fill in the blank: The equilibrium constant and the reaction quotient have the same ____________, but the concentrations in the ____________ can be the concentrations at ___________, not just at _________

Answer 5

mathematical form, reaction quotient, anytime, equilibrium

(The equilibrium constant and the reaction quotient have the same mathematical form, but the concentrations in the reaction quotient can be the concentrations at any time, not just at equilibrium)

Question 6

If Q > Keq what does this say about the equilibrium? does the reaction shift?

Answer 6

The system is NOT at equilibrium and the system will produce more reactants to reach equilibrium (shift to the left)

Question 7

What is the relationship between the dissociation of acetic acid and water?

Answer 7

acetic acid does not dissolve much in water

Question 8

If Keq > Q what holds true of the system?

Answer 8

The reaction is not at equilibrium and will shift to the right

Make sure Keq is on the left side of >/< symbol to match up to arrow

Question 9

If Keq = Q then what hold true of the system?

Answer 9

System is at equilibrium and will NOT shift

Question 10

What will increase the production of ammonia from nitrogen and hydrogen gas?

Answer 10

cooling down the reaction, adding more reatants, increasing partial pressure of reactants

Question 11

True or false: the addition of an inert gas causes perturbation in a gaseous equilibrium

Answer 11

false

Question 12

True or false: a gaseous equilibrium respond to an increase in pressure by shifting to the side of equilibrium with fewer moles of gas particles

Answer 12

true

Question 13

True or false: Increasing the concentration of products in a system at equilibrium makes the equilibrium constant larger

Answer 13

False

Question 14

True or false: adding more aqueous products to a system at equilibrium causes a shift toward the reactants

Answer 14

True

Question 15

Are all exothermic processes spontaneous?

Answer 15

No

Question 16

True or false: if the temperature increases during a process, that process is spontaneous

Answer 16

true

Question 17

Fill in the blank: a spontaneous process occurs under a ______________

Answer 17

Specific set of conditions

Question 18

What type of reaction will proceed without any outside intervention?

Answer 18

One that is spontaneous in the forward direction

Question 19

What are the units for enthalpy?

Answer 19

kj/mol

Question 20

What type of process can do work and what type of process requires work?

Answer 20

A spontaneous process can do work and a nonspontaneous process requires work

Question 21

True or false: a spontaneous process can happen slowly

Answer 21

Yes, speed of rxn does not change whether the process is spontaneous or not

Question 22

What is a restatement of the first law of thermodynamics?

Answer 22

Energy can be converted to a different form but not created or destroyed

Question 23

What is the third law of thermodynamics?

Answer 23

The entropy of a perfect crystalline substance is equal to zero at absolute zero

Question 24

True or false: the following relationship is correct: Ssurr=-Hsys/T

Answer 24

True

Question 25

True or false: For two substances in the same phase, and with similar molar masses, the substance with less complex structure has greater standard entropy

Answer 25

False

Question 26

Fill in the blank: A molecule of O2 has less ______ _______ than a molecule of F2

Answer 26

Motional Energy

Question 27

Fill in the blank: a higher temperature correlates with a ______ average molecular speed

Answer 27

Higher

Question 28

What is entropy a measure of?

Answer 28

How spread out or dispersed the system’s energy is

Question 29

Fill in the blank: For two monatomic species, the one with the larger molar mass has the ________ standard entropy

Answer 29

Greater

Question 30

Is there a difference between Gibbs free energy and free energy?

Answer 30

No, but make sure they are in fact asking about free energy and NOT standard free energy

Question 31

What is the standard free energy change of a reaction?

Answer 31

It is the energy change in a reaction that occurs during standard-state conditions

Question 32

When is Gibbs free energy spontaneous? When is it at equilibrium?

Answer 32

DeltG>0 non-spontaneous in the forward direction, spontaneous in the reverse direction DeltG<0 spontaneous in the forward direction, non-spontaneous in the reverse direction DeltG=0 reaction is at equilibrium, not spontaneous in any direction

Question 33

When both enthalpy and entropy change are negative, what is the spontaneity of the reaction?

Answer 33

It can be either spontaneous or nonspontaneous depending on the temperature

Question 34

For the following reaction, Kp=0.113 at 25*C, and the standard free energy change is 5.4 kj/mol. If Todd does an experiment where the initial pressures are PN2O4=0.452 atm and PNO2=0.122 atm, what are the correct units of the free energy change of the reaction? N2O4(g)-->2NO2(g)

Answer 34

kj/mol

Question 35

Fill in the blank: If Q is positive then _________ are favored at equilibrium

Answer 35

Products

Question 36

How is free energy change of a reaction calculated?

Answer 36

DeltG=G°+RTlnQ

Question 37

True or false: Even if a system starts out with all reactants and products in their standard states, as soon as the reaction begins, standard state conditions no longer exist.

Answer 37

True

Question 38

True or false: the sign of DeltG tells us the same thing as the comparison of Q and K values

Answer 38

True

Question 39

Choose: The size of the equilibrium constant (does/does not) vary with temperature

Answer 39

Does

Question 40

What is the relationship between the equilibrium constant and the standard free energy?

Answer 40

When DeltG°=0 then K = 1 When DeltG°>0 then K < 1 When DeltG°<0 then K > 1