3.1.11 Electrode potentials and electrochemical cells

Question 1

What is a half cell ?

Answer 1

It is half of one electrochemical cell, it is constructed of a metal dipped in its ions

Question 2

When is a platinum electrode used ?

Answer 2

When you have a half cell with 2 aqueous ions, it is used as it. is inert and a metal conductor

Question 3

How is an electro chemical cell created ?

Answer 3

By connecting two half cells together using a wire, voltmeter and salt bridge

Question 4

How do electrons move in an electrochemical cell ?

Answer 4

Electrons flow from a more reactive metal to a less reactive metal

Question 5

What is a salt bridge ?

Answer 5

A filter paper with saturated KNO3 solution

Question 6

Which side are electrons on in a half equation in the reduced form ?

Answer 6

The left

Question 7

What acronym can be used to measure which half cell undergoes oxidation and reduction ?

Answer 7

NO PRoblem
Negative half cell will undergo oxidation
Positive half cell will undergo reduction

Question 8

If a half cell undergoes oxidation, will the equation be flipped ?

Answer 8

Yes, the equation will be flipped

Question 9

How do you find the overall cell equation ?

Answer 9

Combine the 2 half cell equations

Question 10

What is the standard hydrogen electrode (SHE) used for ?

Answer 10

It is used as a reference to measure standard electrode potentials

Question 11

What is the electrode potential of a standard hydrogen electrode ?

Answer 11

0.00V

Question 12

What standard conditions are used in a SHE ?

Answer 12

• 298K
• 100kPa
• 1 moldm-3 (Conc of ions)
• 0.5 Mol of H2SO4 or 1 mol of Hal

Question 13

What does the electrochemical series show ?

Answer 13

A list of half cell reactions and their electrode potentials

Question 14

In an electrochemical series, the left side shows ?

Answer 14

Oxidising agents, at top left is most powerful

Question 15

In an electrochemical series, the right side shows?

Answer 15

Reducing agents, at the bottom right is the most powerful

Question 16

What is an oxidising agent ?

Answer 16

Substances that oxidise other species, gain electrons and are themselves reduced

Question 17

What is a reducing agent ?

Answer 17

A substance that reduces another atom or ion by causing it to gain electrons. A reducing agent itself gets oxidised – it loses/donates electrons

Question 18

How do you calculate standard cell potential ?

Answer 18

E0 cell = EO reduced - EO oxidised

Question 19

What is a cell notation used for ?

Answer 19

It is used to simplify how we draw the set up of the cell

Question 20

How are cell notations written ?

Answer 20

Reduced form|Oxidised form||Oxidised form| Reduced form

Question 21

What do the solid lines in a cell notation show ?

Answer 21

A physical state change

Question 22

What does the double line in a cell notation show ?

Answer 22

The salt bridge

Question 23

A positive EO cell value means ?

Answer 23

The reaction is feasible

Question 24

What is an electrochemical series ?

Answer 24

A list of electrode potentials in numerical order

Question 25

Give an equation for the reaction that occurs at the positive lithium cobalt oxide electrode

Answer 25

Li+ + CoO2 + e– → Li + CoO2–

Question 26

Give an equation for the reaction that occurs at the negative lithium electrode

Answer 26

Li→Li+ + e–