Electrochemistry

Question 1

What is measured by electrode potential

Answer 1

• tendency of a substance to be oxidised or reduced

Question 2

Types of half cells

Answer 2

• metal and its ion
• non metal and its ion
• ion - ion

Question 3

What is standard electrode potential

Answer 3

• the standard electrode potential of a half cell is defined as the potential difference between a standard hydrogen electrode and the half cell in which the reacting species in the solution are at molar concentrations of 1 mol dm^-3, 298K and gaseous species at pressure of 1 bar

Question 4

Significance of electrode potential values

Answer 4

• more positive the electrode potential, the more likely reduction will occur
• more negative the electrode potential, the more likely oxidation will occur

Question 5

• Cell notation/ Cell diagram
• Electrode potential of a cell

Answer 5

• oxidation half-cell II reduction half-cell
• E_cell = E_reduction — E_oxidation

Question 6

Spontaneity of reaction

Answer 6

• G = -nFE_cell
• E_cell>0, G<0, reaction is spontaneous
• E_cell<0, G>0, reaction is not spontaneous

Question 7

Factors affecting selective discharge of substances

Answer 7

• state of electrolyte
• electrode potential
• relative concentration of ions
• nature of electrodes

Question 8

Industrial process involving electrolysis

Answer 8

• anodising of aluminium
• electrolytic purification of copper
• electrolysis of brine using a diaphragm cell

Question 9

Faraday’s laws of electrolysis and equation

Answer 9

• the mass of a substance produced at an electrode during electrolysis is directly proportional to the quantity of electricity passed
• number of Faraday’s required to discharge one mole of an ion at an electrode is equal to the charge of the ion
• n_eF = It