electrolysis

Question 1

what does electrolysis look at?

Answer 1

the use of electrical energy to make chemical energy (ie chemicals)

Question 2

what is electrolysis used in?

Answer 2

recharging batteries
industrial production of chemicals
electroplating

Question 3

how is the ECST interpreted?

Answer 3

non-spontaneous uphill gradient

shortest gradient

Question 4

discharging

Answer 4

chemical to electrical

Question 5

recharging

Answer 5

electrical to chemical

Question 6

electrolyte can be:

Answer 6

molten, aqueous

Question 7

if molten:

Answer 7

no water, proceed to ECST and ignore water

Question 8

if aqueous:

Answer 8

water needs to be considered

greater than 5M:
lots of ions, less water, water cannot be both oxidant and reductant

less that 5M:
less ions, more water, water can be both oxidant and reductant

Question 9

how to predict products at electrodes

Answer 9

identify all species
circle on ECST
determine shortest uphill gradient

Question 10

down cell

Answer 10

• molten NaCl

- force electrons into non-spontaneous reaction

Question 11

membrane cell

Answer 11

• selectively permeable for Na+
• 5M brine
• must consider if water can react
• must consider the fact Na has been selected for and therefore cannot react until end when it might help form product

Question 12

hall harolt cell

Answer 12

alumina in cryolite to keep temp down to keep alumina molten (cheaper)
anodes are carbon
electrons forced through pick up aluminium ions and form aluminium which flows out
oxide ions react with c at anode and carbon dioxide is produced

Question 13

electroplating

Answer 13

the coating of an object with a metal

Question 14

how does an electroplating cell work?

Answer 14

galvanic anode forces electrons into electrolytic cathode (object)
galvanic cathode attached to electrolytic anode which breaks off to form ions to replenish electrolyte
ions join with electrons on object to become a coating
electrolyte must contain ions that eventually undergo reduction to coat

Question 15

inert electrode

Answer 15

the ions are not replenished and the chemist needs to control this

Question 16

stoich in electroplating

Answer 16

charge is the same as number of electrons

Question 17

what does charge govern?

Answer 17

the mole of electrons required for the metal being deposited

Question 18

anode

Answer 18

positive

Question 19

cathode

Answer 19

negative

Question 20

what is faraday’s study?

Answer 20

the relationship between electrical charge and mass deposited at cathode

Question 21

faradays equations?

Answer 21

Q = I x t
Q= coloumbs 
I= amps 
t= time seconds 

Q = n(e-) x faradays constant

96500Cmol-1

Question 22

primary cell

Answer 22

batteries that cannot be recharge such as galvanic cells- button cell

Question 23

secondary cell

Answer 23

batteries that are rechargeable- operate as both electrochemical and electrolytic cells- phone

Question 24

chemical energy to electrical

Answer 24

discharging, galvanic cell, energy is made

Question 25

electrical to chemical

Answer 25

recharging, electrolytic, energy is required