U3AOS2 - Production of Chemicals by Electrolysis

Question 1

What is an electrolytic reaction

Answer 1

Reactions that convert electrical energy into chemical energy - by forcibly reversing spontaneous redox reactions with the use of electricity

Question 2

Applications of Electrolysis (3x)

Answer 2

• Rechargeable Batteries
• To produce substances not found in nature (Na(s) or Cl2(g))
• To electroplate substances

Question 3

Molten Electrolytes

Answer 3

Electrolytes at very high temperatures, where the ionic compounds have melted becoming a liquid of its constituent ions (e.g. NaCl(s) to Na+(l) and Cl-(l))

Question 4

Aqueous Electrolytes

Answer 4

Formed when the electrolyte dissolves in water

Note - water is always present in an aqueous electrolyte - and thus can participate in the electrolytic reaction

Question 5

General Operating Principles of Electrolysis - Position of Electrodes

Answer 5

May be in the same cell - as the electrolytic reactions are non-spontaneous, and thus, the reactants will not spontaneously react

Question 6

General Operating Principles of Electrolysis - Products Formed

Answer 6

Will spontaneously react, and thus, should be separated to avoid an undesired reaction

Question 7

General Operating Principles of Electrolysis - Anode

Answer 7

Positively Charged - oxidation occurs (loses electrodes)

Question 8

General Operating Principles of Electrolysis - Cathode

Answer 8

Negatively Charged - reduction occurs (loses electrodes)

Question 9

General Operating Principles of Electrolysis - Purpose of Electrolyte

Answer 9

Allows the movement of charged particles between electrodes

Question 10

General Operating Principles of Electrolysis - Power Supply (and what sides are the electrodes wired to)

Answer 10

Required for the electrolytic reaction to occur

The anode will be wired to the positive side
The cathode will be wired to the negative side

Question 11

Galvanic Cells vs Electrolytic Cells - Energy Transformations

Answer 11

Galvanic Cells - Chemical to Electrical
Electrolytic Cells - Electrical to Chemical

Question 12

Galvanic Cells vs Electrolytic Cells - Charge of Anode/Cathode

Answer 12

Galvanic Cells - Anode is negative, Cathode is positive
Electrolytic Cells - Anode is positive, Cathode is negative

Question 13

Galvanic Cells vs Electrolytic Cells - Direction of Electron Flow

Answer 13

From the Anode to the Cathode (for both)

Question 14

Galvanic Cells vs Electrolytic Cells - Location of Oxidation & Reduction

Answer 14

Oxidation @ Anode
Reduction @ Cathode

Same regardless of galvanic vs electrolytic

Question 15

Galvanic Cells vs Electrolytic Cells - Separation of Half Cells

Answer 15

Galvanic Cells - must be separated
Electrolytic Cells - can be combined

Question 16

Galvanic Cells vs Electrolytic Cells - Exothermic or Endothermic

Answer 16

Galvanic Cells are Exothermic
Electrolytic Cells are Endothermic

Question 17

Faraday Laws - Determining Quantity of Charge

Answer 17

Question 18

Faradays Laws - Finding moles of e(-)

Answer 18

Question 19

Electroplating

Answer 19

Process of depositing a layer of metal on another metal through electrolysis

The object that is being electroplated is always the anode

Question 20

Reasons for Electroplating

Answer 20

To improve electrical conductivity, strength, alter appearance and to protect metal from corrosion

Question 21

Purpose of a Membrane in Electrolysis

Answer 21

Can be used to prevent unwanted reactions from occurring

because the products of a non-spontaneous redox reaction will want to spontaneously recombine