Electrode Potentials and Electrochemical Cells

Question 1

Electrochemical Series

Answer 1

List of electrode potentials in numerical order

Question 2

Half Cell

Answer 2

Container in which oxidation or reduction occurs

Question 3

Salt-bridge

Answer 3

Allows connection between the 2 half cells and maintains charge balance

Question 4

Electrode

Answer 4

Can act as either oxidising or reducing agent

Question 5

Voltmeter

Answer 5

Measures voltage generated by combination of half cells (EMF)

Question 6

Electrochemical Cells

Answer 6

Combination of 2 half cells

Question 7

How do electrons flow?

Answer 7

From a more reactive to a less reactive metal

Question 8

NO PR

Answer 8

Negative-Oxidation(-E°) Positive-Reduction (+E°)

Question 9

Standard Electrode Potential E°

Answer 9

Voltage measured under standard conditions when the half cell is connected to a Standard Hydrogen Electrode

Question 10

Standard Conditions against a SHE

Answer 10

1) 1.00mol dm-3 concentration
2) 298K (25°)
3) 100kPa

Question 11

Standard Cell Potential (E°cell)

Answer 11

E° cell = E° reduced - E° oxidised

Question 12

Why might EMF values be different?

Answer 12

Non-standard conditions were used

Question 13

Cell notation

Answer 13

reduced form I oxidise form I I oxidised form I reduced form

Question 14

Use of Electrochemical Cell

Answer 14

Batteries providing electricity

Question 15

Lithium Cell

Answer 15

Positive Electrode: Li+ + CoO2 + e- —-> Li+[CoO2]-
Negative Electrode: Li —> Li+ + e-

Question 16

How are batteries recharged?

Answer 16

Current supplied forces electrons in opposite direction around circuit.

Question 17

The reaction of Hydrogen being Oxidised at the anode entering the alkaline hydrogen-oxygen fuel cell

Answer 17

2H2(g) + 4OH- (aq) —-> 4H2O (l) + 4e-

Question 18

The reaction of Oxygen being Reduced at the cathode

Answer 18

O2(g) + 2H2O (l) + 4e- —–> 4OH-

Question 19

Overall reaction of the H2 and O2 making water

Answer 19

2H2(g) + O2(g) —-> 2H2O (g)

Question 20

Fuel Cell Advantages

Answer 20

More efficent than internal combustion engines
Do not need to be recharged, only need Oxygen and Hydrogen

Question 21

Fuel Cell Disadvantages

Answer 21

Hydrogen is highly flammable
Expensive
Fossil fuels are used to pass water through electrolysis