Electrochem: Cells

Question 1

Define Voltaic Cells

Answer 1

• chemical to electrical energy
• Spontaneous electrochemical reaction that produce electricity
• Have salt bridge

Question 2

Cathode Electrode (voltaic cell)

Answer 2

• Pos. electrode
• Reduction occurs
• Gains mass

Question 3

Anode Electrode (voltaic cell)

Answer 3

• Neg. electrode
• Oxidation occurs
• Loses mass

Question 4

Define Inert Electrode

Answer 4

Do not undergo redox, solid in solution

Ex. Carbon or platinum

Question 5

Use of salt bridge in voltaic cell:

Answer 5

Electrolytes from the solutions move thru the salt bridge to prevent side reactions

Question 6

Where do cations travel

Answer 6

to Cathode

Question 7

Where do Anions travel

Answer 7

to Anode

Question 8

Why does the cathode gain mass?

Answer 8

It is gaining electrons (red) which increases mass

Question 9

Use of external circuit

Answer 9

helps electrons move from anode to cathode

Question 10

Cell notation (voltaic)

Answer 10

Anode/Anode electrolyte//Cathode electrolyte/Cathode

Question 11

Define cell potential

Answer 11

measure of potential difference between two half cells (RA and OA)

Question 12

Cell potential net formula

Answer 12

Enet= E(SOA) - E(SRA)

Question 13

Positive Enet means

Answer 13

spontaneous reaction and the electrical potential that is generated

Question 14

Negative Enet means

Answer 14

non-spontaneous reaction and needs electricity

Question 15

What is a fuel cell?

Answer 15

• type of voltaic cell
• Uses H2 and O2 to produce electricity and water
• O2 + 2H2 > 2H2O

Question 16

What happens at anode (fuel):

Answer 16

H2 is oxidized and loses electrons

Question 17

What happens at cathode(fuel):

Answer 17

O2 is reduced and gains electrons

Question 18

What is the electrolyte used in fuel cells:

Answer 18

OH-

Question 19

How to prevent corrosion

Answer 19

Galvanizing or Impressed Current System/cathodic protection

Question 20

Galvanizing

Answer 20

easily rusted metals are covered by a protective cover (sacrificial anode) of zinc which becomes the anode of the cell and is oxidized before the original metal

Question 21

Impressed Current System (ICS)/Cathodic Protection

Answer 21

Uses battery or generator so that electric current supplies electrons to stimulate corroding anode. Anode does not corrode bcs it is not losing electrons

Question 22

Electrolytic Cells

Answer 22

• Electrical energy to chemical energy
• process called electrolysis
• Non-spon reaction
• Uses energy source (battery) making cathode more negative than anode
• Negative E value
• One container (one solution)
  Ex. recharging battery, electroplating, chloralkai process

Question 23

Anode (electrolytic)

Answer 23

• Pos. Electrode

- loses mass

Question 24

Cathode (electrolytic)

Answer 24

• Neg Electrode

- Gains mass

Question 25

What is the Chlor-alkali process?

Answer 25

- Electrolysis of NaCl - Cl acts as SRA instead of H2O, process is called half cell overvoltage - Cl gas is produced at the anode - H2O stays as SOA

Question 26

Faraday's Law

Answer 26

- Electrons pass thru external circuit in electrolysis | - Flow of electrons is a current = I, unit is A (A= C/S)

Question 27

Faraday's Constant

Answer 27

9.65 x10^4 C/mol

Question 28

Electroplating

Answer 28

- Applying electric current | - Measuring ratio of flow of electric charge over a measured time to get mass of substance

Question 29

In electroplating, cathode...

Answer 29

gains mass and is always being plated