C6 Electrolysis

Question 1

why cannot solid ionic compounds cannot conduct electricity .

Answer 1

The ions are locked in place and are not free to move , they are held together by strong electrostatic forces of attraction .

Question 2

Why can ionic compounds that are molten or dissolved in water conduct electricity ?

Answer 2

the forces of attraction are broken and the ions are free to move .

Question 3

what are electrolytes

Answer 3

compound that is broken down by electrolysis and therefore can conduc electricity

Question 4

what are the two ions n lead bromine

Answer 4

Pb2+ Br-

Question 5

how many electrodes are in electrolysis

Answer 5

two

Question 6

what are the electrodes made of

Answer 6

conducting materal such as graphite or a metal .

Question 7

what is the negative electode

Answer 7

cathode

Question 8

what is the positive electrode

Answer 8

anode

Question 9

what happens pb2+ (lead) whta type of reaction is ths

Answer 9

the Pb+ gain two electrons from Pb atoms this is called Reduction
Pb—>pb2+ +2e-

Question 10

what happens in reduction

Answer 10

u gain electrons

Question 11

What happens to Br-

Answer 11

Br- looses oe electron to for Br atoms this is called oxidation

Question 12

what happens in oxidiation

Answer 12

loose electrons

Question 13

what is electrolysis

Answer 13

electrolysis is the breakdown of a substance conataining ions by electricity

Question 14

how are metals less reactive than carbon extracted

Answer 14

metals less reactive than carbon cna be extracted by reduction with carbon .

Question 15

how are metals more reactive than carbon extracted.

Answer 15

Metals more reactive than carbon can be extracted using electrolysis .

Question 16

What does aluminium oxide contain

Answer 16

it contains aluminum ions (AL3+) and Oxide ions (02-)

Question 17

why is aluminium oxide not produced by the electrolysis of an aqueous solution ?

Answer 17

As aluminium oxide is insoluble in water .

Question 18

what is the first step of electrolysis with aluminium oxide

Answer 18

aluminium oxide is mixed with cryolite .

Question 19

why is aluminium oxide mixed with cryolite

Answer 19

as it lowers the melting point of aluminium oxide as it as a high a very high melting point , reducing the amount of energy needed and saves money for electrolysis .

Question 20

what are the anode and cathode made of and why ?

Answer 20

Made of graphite , as it is a very good conductor of electricity and has a very high melting point .

Question 21

where are the AL3+ ions attracted to.

Answer 21

AL3+ ions are attracted to the cathode (the negative electrode .

Question 22

Give the half equation at the cathode for aluminium oxide what type of reaction is it and why

Answer 22

AL3+ + 3E- arrow AL - it is a reduction as each ion gains three electrons and forms aluminium atoms .

Question 23

Why is aluminium ions attracted to the negative elctorde

Answer 23

As aluminium ions are metals so are positively charged so are atracted to the negative electrode as opposites attract and gain three electrons ,

Question 24

where are oxide ions attracted to in alumnium oxide

Answer 24

02- ions are attracted to the anode (positive terminal)

Question 25

what is the half equation at the anode for aluminium oxide . What type or reaction is it and why

Answer 25

202-4e-arrowO2 it is oxidation as the oxide ions loses two electrons to form an oxygen atom .

Question 26

Why must the anode be replaced regularly | wrtie the equation for this .

Answer 26

as the oxygen molecules produced at the anode react with the graphite (carbon) , forming C02 gas . c+02arrow co2

Question 27

why do u need to double everything at the anode for aluminium oxide

Answer 27

as oxygen atoms at the anode pair up up to form oxygen molecules .

Question 28

give two reasons why electrolysis is expensive

Answer 28

- Melting the compounds such as aluminium oxide requires a great deal of energy . - A lot of energy is required to produce the electric current .

Question 29

Meaning of aqueous solutions

Answer 29

dissolved in water

Question 30

water molecules ionise (split) forming what ?

Answer 30

hydrogen ions H+ | and hyrdoxide ions OH-

Question 31

what is the formula for Copper sulfate solution

Answer 31

CuSO4(aq)

Question 32

what does CuSO4 split into

Answer 32

CU2+ SO42- and H+ -hydrogen ions and OH- hydroxide ions because aqueous

Question 33

What are the two possible things that can be produced at the cathode for copper sulfate solution .

Answer 33

Cu2+ | or H+

Question 34

which one is porduced at the cathode at copper sulfate solution and why .

Answer 34

Hydrogen is produced at the cathode if the metal is more reactive than hydrogen . Copper is less reactive than hydrogen os i produced

Question 35

What is produced at the anode for copper sulfate solution

Answer 35

oxygen gas , usually , when carrying out electrolysis on an aqueous solution , we usually get oxygen produced at the anode .

Question 36

Why should electrodes be inert

Answer 36

As it is important that electrodes do notg react witht he chemicals that were making an electrolysis .

Question 37

what is the meaning of inert

Answer 37

do not react .

Question 38

what material is often used as inert electrodes and why

Answer 38

platinum is ofen used as inert electrodes as platinum is a very unreactive material .

Question 39

What is the half equation at the cathode for copper sulfate solution

Answer 39

Cu2+ +2e- ---> Cu

Question 40

what type of reaction is at the cathode for copper sulfate solution and why

Answer 40

it is a reduction as copper ions gain 2 electrons to become copper attoms .

Question 41

what is the half equation for the anode for copper sulfate solution and why . What type of reaction is it ?

Answer 41

40H----> 02+ 2H20 + 4e- | hydroxide ions react to make oxygen and water and use 4 electrons in the process so it is an OXIDATION REACTION .

Question 42

What is the formula for sodium chloride

Answer 42

NaCl

Question 43

what two ions is sodium chloride made up of

Answer 43

Na+ sodium ions and Cl- and chloride ions and H+-hrdogen ions and OH- hydroxide ions as it is in an aqueous solution .

Question 44

What are the two potential discharges at the cathode for sodium chloride

Answer 44

Na+ sodium ions | H+ hydrogen ions

Question 45

What is produced at the cathode for sodium chloride

Answer 45

Hydrogen is prooduced at the cathode if the metal is more reactive than hydrogen . Sodium is MORE reactive than hydrogen so HYDROGEN is produced at the CATHODE

Question 46

What are the two potential discharges at the anode for sodium chloride

Answer 46

Cl- chlorine ions | OH- hydroxide ions

Question 47

what is produced at the anode for sodium chloride

Answer 47

If the aqueous solution contains halide ions (Cl-,Br-,I-) then the halogen will be produced at the anode otherwise oxyegn .As the sodium chloride contains chloride ions , CHLORINE GAS will be produced at the ANODE .

Question 48

What is thehalf equation and reaction at the cathode for sodium chloride

Answer 48

2H+ + 2e ---> H2 The hydrogen ion is gaining one electron to become a hyrdogen atom so is a REDUCTION . However hydrogen atoms pair to make hydrogen molecules so everything doubles .

Question 49

What is the half equation and reaction at the anode for sodium chloride

Answer 49

2CL- --->cL2 +2e- The chloride ion looses one electron to form a chloride atom so it is an OXIDATION , however , chlorine atoms pair to form chlorine molecules so everything doubles .

Question 50

what is a positively charged ion called

Answer 50

cation

Question 51

what is a negatively charged ion called

Answer 51

anion