Electrolysis

Question 1

What is electrolysis

Answer 1

when a molten of aqueous ionic compound is decomposed using and electric current

Question 2

why cant covalent compounds undergo electrolysis

Answer 2

because they do not conduct electricity

Question 3

what is an Anode

Answer 3

a positive electrode

Question 4

what is a cathode

Answer 4

negative electode

Question 5

what is a anion

Answer 5

negatively charged ion anode

Question 6

what is a cation

Answer 6

positively charged ion attracted to cathode

Question 7

how does electrons flow in electrolytic cell

Answer 7

from anode to cathode

Question 8

what do aqueous solution have that contribute to electrolysis

Answer 8

water that spilt into H+ and OH- ions

Question 9

Explain what occurs in the cathode

Answer 9

• H+- and Metal ions are attracted to the cathode
• product form is dependant on reactivity series
  is metal is more reactive than hydrogen then hydrogen is formed (bubbling) - exceptions copper silver gold

Question 10

What happens in the anode

Answer 10

• OH- and non metal ions are attracted to the anode
• product formed is dependant how ion is discharged
• at anode oxygen is present unless metal ion is a halide.

Question 11

explain the products of acidified water

Answer 11

hydrogen ion at cathode and oxygen at anode

Question 12

what is a binary ionic compound

Answer 12

two element joined together by ionic bonding and when they are melted they can conduct electricity and carry a charge

Question 13

explain the electrolysis of lead bromide

1. what are the ions present
2. what ions go where
3. what is reduced and oxidised
4. what can u observe

Answer 13

1. ions present are Pb+ and H+ / OH- and Br-
2. Pb+ and H+ ions are attracted to the cathode
3. Pb is reduced as it is less reactive than hydrogen
4. grey lead deposit at bottom of electrode
5. OH- and Br- is attracted to the anode
6. Br- is oxidised as it is a halide ion
7. Brown vapour is given off by the bromide

Question 14

how can you predict an electrolysis reaction of molten ionic compounds

Answer 14

at cathode metals are always formed and at anode non metal always formed

Question 15

what are the results of the electrolysis of copper sulphate

Answer 15

copper is formed at the cathode as copper is less reactive than hydrogen and oxygen gas is produced at the anode as halide ions are not present

Question 16

what is the method of electrolysis with inert electrodes

Answer 16

• pour copper sulfate into beaker
• place graphite rods attaching to opposite terminals
• fill two small tubes with copper sulfate and position over electrodes
• test gas produced using glowing splint and burning splint

Question 17

Explain the method of electrolysis with copper electrodes

Answer 17

• pour copper sulfate in beaker
• measure mass of copper foil and attach to negative and positive end of terminal and dip into copper sulfate
• adjust power station and leave it for 30mins
• remove electrodes and dry so results accurate

Question 18

what are we recording in the copper electrode experiment

Answer 18

change in mass of electrodes and currents used

Question 19

what are recording in the inert electrode experiment

Answer 19

results of gas test and what is produced at each electrode

Question 20

results of copper electrode: why is there a mass change

Answer 20

because copper is oxidised at anode and reduced at cathode therefore anode decreases in mass and cathode increases in mass as anode passes on copper to cathode

Question 21

results copper electrode: why is mass constant

Answer 21

as copper deposited at negative electrode is the same as the copper lost from positive electrode

Question 22

how is copper purified

Answer 22

copper is extracted from its ore using reduction by carbon then go through electrolysis to purify it using copper electrodes

Question 23

what does the … look like at the start of purifying copper

1) anode
2) cathode
3) electrolyte

Answer 23

1) big lump of impure copper
2) copper sulfate solution ( Cu+)
3) cathode contains thin piece of pure copper

Question 24

what happens during the process of electrolysis or purifying copper

Answer 24

impure copper at anode is oxidised and dissolves with electrolyte to form copper ions then the copper ions are reduced at the copper cathode and the layer of pure copper gets thicker any impurities sink to the bottom forming a sludge

Question 25

what is the slude

Answer 25

highly valuable material that is refined as it contains small precious metals