Elecctrochemistry

Question 1

Electrochemical cells

Answer 1

Contained systems where oxidation-reduction reactions occur

Question 2

Galvanic/Voltaic cells house what kind of reaction?

Answer 2

Spontaneous

Question 3

Electrolytic cells house what kind of reaction?

Answer 3

Nonspontaneous

Question 4

Electromotive force (emf)

Answer 4

Voltage or electrical potential difference of the cell

Question 5

If emf is positive

Answer 5

The reaction is spontaneous

Delta G<0

Question 6

If emf is negative

Answer 6

The reaction is nonspontaneous

Delta G>0

Question 7

Half cells

Answer 7

Two electrodes placed in separate compartments

Question 8

Salt bridge

Answer 8

Made of inert salt - permits exchange of cations and anions so that the excessive charge won’t accumulate on both sides

Question 9

Rules of a cell diagram

Answer 9

1. )Reactants and products are always listed left to right in anode, anode soln, cathode soln, cathode
2. ) Single vertical line means phase boundary
3. )Double vertical is the presence of a salt bridge

Question 10

How does the current flow?

Answer 10

From cathode to anode

Question 11

Electrolysis

Answer 11

Oxidation-reduction drivedn by external voltage source where chemicals are decomposed

Question 12

Electrodesposition equation

Answer 12

molM=It/nF

n=oxidation state of the compound needed

Question 13

Concentration cell

Answer 13

A galvanic cell that ahs two half-cells connected by a conductive material, allowing spontaneous oxidation-reduction to proceed
Chemically identical electrodes

Question 14

Rechargable cell/battery

Answer 14

Functions as both a galvanic cell and electrolytic cell

Question 15

Lead-acid battery/lead storage battery

Answer 15

Rechargeable battery
Voltaic/Galvanic cell- two half-cells 
Pb anode and PbO2 cathode connected by H2SO4
When fully charged-
Two PbSO4 with dilute H2SO4

Question 16

What happens when a lead-acid battery is charging?

Answer 16

It is part of a electrolytic circuit and equations change directions

Question 17

Energy density

Answer 17

Measure of a battery’s ability to produce power as a function of its weight

Question 18

What is the energy density of lead-acid batteries compared to others ?

Answer 18

Low

Question 19

Anode in lead-acid batteries?

Answer 19

Pb

Question 20

Cathode in lead-acid batteries?

Answer 20

PbO2

Question 21

Anode in nickel-cadmium batteries?

Answer 21

Solid cadmium

Question 22

Cathode in nickel-cadmium batteries?

Answer 22

Nickel (III) oxide-hydroxide

Question 23

What has a higher energy density, nickel-cadmium batteries or lead-acid?

Answer 23

Nickel cadium

Question 24

Surge current

Answer 24

Peridos of large current early in the discharge cycle

Question 25

Anodes considered what charge in galvanic cell?

Answer 25

Negative (low electron potential)

Question 26

Cathode considered what charge in galvanic cell?

Answer 26

Positive (high electron potential)

Question 27

What way does current flow in the anode-cathode galvanic cell?

Answer 27

From Cathode to anode

Question 28

Anode considered what charge in electrolytic cell?

Answer 28

Positive

Question 29

Cathode of electrolytic cell is what charge in electrolytic cell?

Answer 29

Negative

Question 30

Which way do anions always flow?

Answer 30

To anode

Question 31

Which way do cations always flow?

Answer 31

To cathode

Question 32

Where do reduction and oxidation always take place?

Answer 32

Anode=oxidation | Cathode=reduction

Question 33

Which way do electrons always flow?

Answer 33

From anode to cathode?

Question 34

Which way does current always flow?

Answer 34

Cathode to anode

Question 35

Reduction potential

Answer 35

Measured in volts compared relative to the standard hydrogen electrode (SHE) which has a potential of 0 V

Question 36

Reduction potential

Answer 36

Defined as the tendancy of a species to gain electrons and be reduced

Question 37

More positive potential means?

Answer 37

Greater tendency to be reduced

Question 38

Standard reduction potential (E(red))

Answer 38

Measured under standard conditions 25 degrees C 1 atm 1 M

Question 39

In galvanic cells, because electrons flow from anode (less positive) to cathode (more positive=wants to be reduced):

Answer 39

Reaction is spontaneous and Delta G is negative

Question 40

In electrolytic cells, electrode with more positive reduction potential is forced to be oxidized, so it is the:

Answer 40

Anode

Question 41

In electrolytic cells, electrode with less positive reduction potential is forced to be reduced and it is the?

Answer 41

Cathode

Question 42

What is the Delta G of the electrolytic cell?

Answer 42

Positive, non-spontaneous | Negative Ecell value

Question 43

How to get oxidation potential from reduction potential?

Answer 43

Reverse the sign

Question 44

Standard electromotive force (emf)

Answer 44

E(cell)=E(red,cathode)- E(red, anode)

Question 45

What is the Delta G of galvanic cell?

Answer 45

``` Negative Delta G Positive E(cell) values ```

Question 46

What species are included in the reaction quotient

Answer 46

The ones in solution

Question 47

If equilibrium constant for the reaction is between 0 and 1

Answer 47

E(cell) will be negative because ln between 0 to 1 is negative Electrolytic cell, +G, nonspontanteous

Question 48

If equilibrium constant is greater than 1

Answer 48

E (cell) will be positive because ln greater than 1 is positive Galvanic cell, -G, spontaneous

Question 49

What does a positive Keq mean?

Answer 49

Equilibrium lies far right

Question 50

What charge is reduced in electrolytic cells?

Answer 50

More positive reduction potential means it will be oxidized at the anode