Chapter 8 - Electrolysis

Question 1

Electrolysis

Answer 1

The use of an electrical current to force a non-spontaneous chemical reaction. Used to decompose a compound into its individual elements.

Question 2

Brine

Answer 2

Highly saturated salt water.

Question 3

Coulomb (C)

Answer 3

The unit for electrical charge.

Question 4

Electric Charge

Answer 4

A physical property of a particle which determines how it behaves in an electromagnetic field.

Question 5

Electrolytic Cell

Answer 5

A cell which converts electrical energy to chemical energy via electrolysis. Consists of a positive anode (connected to the positive terminal) and negative cathode (connected to the negative terminal) placed in an electrolyte.

Question 6

Electroplating

Answer 6

An application of electrolysis where a thin layer of metal is coated on the surface of another object.

Question 7

Faraday’s Constant (F)

Answer 7

The charge on one mole of electrons, equal to 96500 Coulomb.

Question 8

Faraday’s First Law

Answer 8

The mass of an element deposited at an electrode during electrolysis is directly proportional to the charge, in Coulomb.

Question 9

Faraday’s Second Law

Answer 9

To produce 1 mole of a metal, 1, 2, 3, or some other whole number of moles of electrons must be consumed.

Question 10

Molten Electrolysis

Answer 10

An electrolytic cell where the electrolyte is molten (liquid) rather than aqueous. Only the ions will react at the electrodes.

Question 11

Aqueous Electrolysis

Answer 11

An electrolytic cell where the electrolyte is an aqueous solution. Water can react at the electrodes.

Question 12

Inert Electrode

Answer 12

An electrode that does not partake in the electrolysis process and rather conducts electricity.

Question 13

Reactive Electrode

Answer 13

An electrode which takes part in the electrolysis process. (i.e. the electrode oxidises or reduces itself).

Question 14

Semipermeable Membrane

Answer 14

A membrane that allows some substances to pass through (e.g. sodium ions) while blocking others (e.g. chloride ions). Used in some electrolytic cells to prevent a spontaneous reaction from occurring.

Question 15

General Operating Principles (of electrolytic cells)

Answer 15

• whether the electrolyte is molten or aqueous
• if the electrolyte is molten, whether its mixed with another substance to lower the melting point
• how are the products kept separate and removed from the cell
• is electrode inert or reactive

Question 16

Formula for Mass of Metal Deposited at Cathode During Electrolysis

Answer 16

m(element) = 1/x × Q/F x M(element)