POST EXAM 3

Question 1

What does Ksp represent?

Answer 1

Equilibrium constant for concentrations of dissolved compounds in saturated solution

Ksp indicates the extent to which a compound can dissolve in solution.

Question 2

How does the presence of a common ion affect solubility?

Answer 2

It decreases solubility

Increasing product concentration shifts the equilibrium to the left.

Question 3

What effect does lowering the concentration of a common ion have on solubility?

Answer 3

Higher solubility

Question 4

How does pH affect solubility?

Answer 4

Lower pH leads to higher solubility

The anions get converted to acid (more soluble) → remove product → shift

Especially if the anion is a conjugate base of a weak acid.

Question 5

What happens when Q > Ksp?

Answer 5

Favor reactant formation; compound will precipitate

Question 6

What happens when Q < Ksp?

Answer 6

Favor product formation; soluble compound

Question 7

Define oxidation in redox reactions.

Answer 7

Loss of electrons

Question 8

Define reduction in redox reactions.

Answer 8

Gain of electrons

Question 9

What do oxidation numbers indicate?

Answer 9

How many electrons are lost or gained from the original state

Question 10

What is the oxidation number for elemental state?

Answer 10

0

Question 11

What is the oxidation number for monatomic ions?

Answer 11

Charge of the ion

Question 12

What is the oxidation number for fluorine?

Answer 12

-1

Question 13

What is the oxidation number for oxygen?

Answer 13

-2 (except in peroxides and superoxides)

Question 14

What is the oxidation number for hydrogen in most cases?

Answer 14

+1 (except in metal hydrides)

Question 15

What is the first step in balancing redox reactions?

Answer 15

Write out the half reactions and balance them

Question 16

Under acidic conditions, how do you balance oxygen?

Answer 16

Add H2O to the necessary side

Question 17

Under acidic conditions, how do you balance hydrogen?

Answer 17

Add H+ to the necessary side

Question 18

What is the site of reduction in an electrochemical cell?

Answer 18

Cathode

Question 19

What is the site of oxidation in an electrochemical cell?

Answer 19

Anode

Question 20

What does the salt bridge do in an electrochemical cell?

Answer 20

Helps balance out the charges of each electrode

Question 21

What is the standard reduction potential?

Answer 21

The potential of a reduction reaction in standard states

Question 22

What is the formula for standard cell potential?

Answer 22

E°cell = E°cathode - E°anode

Question 23

What does a more positive E° indicate?

Answer 23

More likely to be reduced

Question 24

What indicates that a reaction is spontaneous?

Answer 24

E°cell > 0

Question 25

What does the Nernst equation help calculate?

Answer 25

Ecell under non-standard conditions

Question 26

What characterizes a concentration cell?

Answer 26

Differing concentrations of an ion | E°cell = 0

Question 27

What type of cells use an external battery source?

Answer 27

Electrolytic cells

Question 28

What type of bonding is present in molecular solids?

Answer 28

Non-covalent intermolecular forces ## Footnote leads to lower melting points, variable hardness and brittleness

Question 29

What are the characteristics of covalent network solids?

Answer 29

Very hard, high melting point, not conductive

Question 30

What type of solids are characterized by metallic bonding?

Answer 30

Metallic solids

Question 31

What are the properties of ionic solids?

Answer 31

Hard, brittle, high melting point, conducts electricity as liquid but not solid

Question 32

What type of electrochemical cell is constructed with differing concentrations of an ion?

Answer 32

Concentration Cells

Question 33

In a concentration cell, what is the sign of the E°cell?

Answer 33

0

Question 34

In a concentration cell, which solution acts as the anode?

Answer 34

More dilute solution

Question 35

In a concentration cell, which solution acts as the cathode?

Answer 35

More concentrated solution

Question 36

What is the primary function of an electrolytic cell?

Answer 36

To drive the flow of e- in the nonspontaneous direction

Question 37

What is used to provide the energy needed for an electrolytic cell?

Answer 37

External battery source

Question 38

In an electrolytic cell, what is the charge of the cathode?

Answer 38

Negative (-)

Question 39

In an electrolytic cell, what is the charge of the anode?

Answer 39

Positive (+)

Question 40

What type of energy is converted into chemical energy in an electrolytic cell?

Answer 40

Electrical energy

Question 42

What is the relationship when Q > 1?

Answer 42

E°cell > Ecell

Question 43

What is the relationship when Q < 1?

Answer 43

E°cell < Ecell

Question 44

What is the relationship when Q = 1?

Answer 44

E°cell = Ecell

Question 45

What does it indicate when Q = K?

Answer 45

Ecell = 0 → equilibrium → no net potential

Question 46

What does E°cell > 0 imply about ΔG° and K?

Answer 46

ΔG° < 0 → K > 1 → product favored at equilibrium → spontaneous under standard conditions

Question 47

What does E°cell < 0 imply about ΔG° and K?

Answer 47

ΔG° > 0 → K < 1 → reactant favored at equilibrium → spontaneous in the reverse direction

Question 48

What does E°cell = 0 indicate about ΔG° and K?

Answer 48

ΔG° = 0 → K = 1 → neither product or reactant favored at equilibrium