Electrolysis

Question 1

What is electrolysis

Answer 1

Electrolysis is a process in which electrical energy, from a direct current (dc) supply, decomposes (breaks down) electrolytes.
The free ions in electrolytes are attracted to the oppositely-charged electrodes connected to the dc supply.

Question 2

What happens during electrolysis

Answer 2

negative ions are discharged at the positive electrode (anode)
positive ions are discharged at the negative electrode (cathode).

Question 3

what is an electrolyte

Answer 3

the liquid that the electric current flows through

Question 4

What is a cathode

Answer 4

a negative electrode where the positive ions (cations) are discharged

Question 5

What is an anode

Answer 5

a positive electrode where the negative ions (anions) are discharged

Question 6

What is a dc

Answer 6

Direct current

The power supply running through the electrolyte

Question 7

Give some examples of cations (that would discharge at the cathode)

Answer 7

Hydrogen (H+)
Ammonium (NH4+)
Sodium (Na+)
Copper(II) (Cu2+)

Question 8

Give some examples of anions (that would discharge at the anode)

Answer 8

Chloride (Cl-)
Oxide (O2-)
Hydroxide (OH-)
Sulfate (SO42-)

Question 9

What happens when ions reach an electrode

Answer 9

They gain or lose electrons. As a result, they form atoms or molecules of elements

Question 10

What happens cations reach the cathode

Answer 10

They gain electrons from the negatively charged cathode

Question 11

What happens when and ions reach the anode

Answer 11

They lose electrons that the positively charged anode

Question 12

What happens during the electrolysis of molten salts

Answer 12

A metal bones at the cathode and a non-metal forms at the anode

Question 13

What happens during the electrolysis of acidified water

Answer 13

H+ ions are attracted to the cathode, gain electrons form hydrogen gas
OH- ions are attracted to the anode, lose electrons and form oxygen gas
(2H20 —— 2H2 + O2)

Question 14

What happens during the electrolysis of dissolved ionic compounds

Answer 14

The electrolyte contains…
🏮Hydrogen ions from the water and positive ions from the compound
🏮Hydroxide ions from the water and negative ions from the compound

Question 15

What determines whether hydrogen or a metal will be produced at the cathode

Answer 15

Position of the metal in the metal reactivity series…
🏮The metal will be produced if the metal is less reactive than hydrogen.
🏮Hydrogen will be produced if the metal is more reactive than hydrogen

Question 16

List the reactivity series so most reactive to least reactive

Answer 16

Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium 
Carbon
Zinc
Iron
Hydrogen
Copper
Silver
Gold