electrolysis

Question 1

why don’t covalent bonds conduct electricity

Answer 1

have no free electrons to carry a charge

Question 2

covalent compounds act as

Answer 2

insulators

Question 3

do ionic compounds conduct electricity

Answer 3

when molten or in solution because they have free ions able to carry a charge

Question 4

during electrolysis, electrons move from ____ to ___

Answer 4

anode

cathode

Question 5

cations

Answer 5

positively charged ions

Question 6

anions

Answer 6

negatively charged ions

Question 7

where do cations in the electrolyte move to

Answer 7

migrate towards the negatively charged electrode

Question 8

negatively charged electrode is the

Answer 8

cathode

Question 9

positevely charged electrode is the

Answer 9

anode

Question 10

anions in the electrolyte migrate towards

Answer 10

the positevely charged electrode

Question 11

binary ionic compounds are

Answer 11

compounds consisting of just two elements joined together by ionic bonding

Question 12

when binary ionic compounds get heated past their melting point, what happens

Answer 12

they become molten and can conduct electricity as their ions can move freely and carry a charge

Question 13

cathode product will always be (for molten compounds)

Answer 13

a metal

Question 14

anode product for molten compounds is

Answer 14

non metal

Question 15

to make the aquoeus solution, what has been done

Answer 15

ionic compound dissolved in water

Question 16

method for electrolysis of lead bromide

Answer 16

Add lead(II) bromide into a crucible and heat so it will turn molten, allowing ions to be free to move and conduct an electric charge

Add two graphite rods as the electrodes and connect this to a power pack or battery

Turn on the power pack or battery and allow electrolysis to take place

Question 17

for lead bromide, what happens at the anode

Answer 17

negative bromide ions move towards positive electrode

at the anode, they lose two electrons and form bromine atoms

bubbling at anode is seen as bromine gas is given off

Question 18

what happens at the cathode with lead bromide

Answer 18

positive lead ions move towards the negative electrode

at the cathode they gain electrons to form a grey lead metal

lead deposits on the bottom of the electrode

Question 19

in the electrolysis of aqueous solutions, water molecules dissociate producing (2)

Answer 19

H+

OH-

Question 20

for aqueous solutions, what happens at the anode

Answer 20

negatively charged OH- ions and non metal ions are attracted to the positive electrode

Question 21

in electrolysis for aqueous solutions, what happens if halide ions are present

Answer 21

they are discharged at the anode, lose an electron and form a halogen

Question 22

what is produced at the cathode in aqueous solution

Answer 22

• positevely charged H+ ions and metal ions are attracted to the cathode, but only one will gain electrons

either hydrogen gas or metal will produce

Question 23

at the cathode, in aqueous solutions, how do you know if a metal or hydrogen is produced

Answer 23

if metal is above hydrogen in the reactivity series, then hydrogen gas will be produced & bubbling is visible

this is because more reactive ions remain in the solution, causing least reactive ion to be discharged

Question 24

if you have a solution of any other common ions other than halides, at the anode, what is produced

Answer 24

oxygen

Question 25

what happens at the cathode of aqueous sodium chloride

Answer 25

both h+ ions and Na+ ions are attracted the Na+ ions are more reactive so H+ gains an electron (reduction) to form hydrogen gas

Question 26

half equation of cathode aqueous sodium chloride

Answer 26

2H+ + 2e- ---> H2

Question 27

what happens at the anode during electrolysis of aqueous sodium chloride

Answer 27

positive anode attracts Cl- and OH- ions as chloride is a halide, it is more reactive and so the OH- stay as an atom Cl combine to make chlorine

Question 28

half equation of anode aqueous sodium chloride

Answer 28

2Cl- --> Cl2 + 2e-

Question 29

what is the remaining solution of aqueous sodium chloride

Answer 29

Na+ and OH- are left over, so they essentially form the solution. SO sodium hydroxide solution is formed (alkaline)

Question 30

for aqueous copper sulfate, what happens at the cathode

Answer 30

Copper (Cu2+) and H+ ions are present, and as copper is below hydrogen, a reduction reaction happens as electrons are gained

Question 31

for aqueous copper sulfate, what happens at the anode

Answer 31

we have SO42- and OH-, as sulafte ions aren't halide, oxygen forms

Question 32

half equation for cathode of aqueous copper sulfate

Answer 32

Cu2+ + 2e- ---> Cu

Question 33

half equation of anode of aqueous copper sulfate

Answer 33

4OH- ---> H20 + O2 +4e-

Question 34

remaining solution of aqueous copper sulfate ?

Answer 34

Hydrogen and sulfate ions are remained, so H2SO4 is formed (sulfuric acid)

Question 35

when you electrolise dilute sulfuric acid as well, what happens at the cathode

Answer 35

there are only hydrogen ions, so they gain an electron to form a hydrogen atom which then joins to make a hydrogen molecule

Question 36

when you electrolise dilute sulfuric acid as well, what happens at the anode

Answer 36

SO42- isn't a halide so oxygen forms

Question 37

half equation of dilute sulfuric acid

Answer 37

2H+ +2e- ---> H2

Question 38

half equation of dilute sulfuric acid at anode

Answer 38

4OH- ---> 2H2O +02