Electrolysis

Question 1

what are electrolytes?

Answer 1

ionic compounds that are melted or aqeous

Question 2

what happens within the conditions of electrolysis?

Answer 2

electrolytes are free to move within the liquid or solution.

Question 3

what is the process of electrolysis?

Answer 3

a process in which electrical energy, from a direct current (dc) supply, decomposes electrolytes

Question 4

describe the movement of ions during electrolysis in molten substances: (3)

Answer 4

-they migrate towards their oppositely charged electrode

• cations move to negatively charged cathode
• anions move to positively charged anode

Question 5

products of electrolysis in molten substances: (2)

Answer 5

• cations gain electrons from the negatively charged cathode

- anions lose electrons at the positively charged anode

Question 6

where are metals and non metals formed in electrolysis? (2)

Answer 6

a metal forms at the cathode

a non-metal forms at the anode.

Question 7

why can pure water conduct electricity?

Answer 7

because a small proportion of its molecules dissociate into ions.

Question 8

describe what happens during the electrolysis of water: (2)

Answer 8

H+ ions are attracted to the cathode, gain electrons and form hydrogen gas

OH- ions are attracted to the anode, lose electrons and form oxygen gas

Question 9

describe the proportions of hydrogen and oxygen given off:

Answer 9

The volume of hydrogen given off is twice the volume of oxygen given off.

Question 10

describe what happens at the CATHODE during the electrolysis of an aqueous solution: (2)

Answer 10

if metal is less reactive than hydrogen = metal produced

if metal is more reactive than hydrogen = hydrogen produced

Question 11

describe what happens at the ANODE during the electrolysis of an aqueous solution: (2)

Answer 11

for the most common compounds oxygen is produced (from the hydroxide ions)

if halide ions (chloride, bromide or iodide ions) are present, then the negatively charged halide ions lose electrons to form the corresponding non-metal halogen (chlorine, bromine or iodine)

Question 12

how is pure copper obtained? (2)

Answer 12

• pure copper rod is connected to the negative terminal of a battery and the impure rod is connected to the positive terminal
• pure copper rod has increases in size while the impure rod has deteriorates, leaving a pool of anode sludge at the bottom of the beaker

Question 13

how does the copper purification process work?

Question 14

define oxidation and reduction and state where they occur: (2)

Answer 14

oxidation: loss of electrons. at anode
reduction: gain of electrons. at cathode