electrolysis and secondary cells (8 Heinmann & 6C)

Question 1

electrolysis

Answer 1

use of electrical energy (DC) to drive non-spontaneous redox reactions in a conducting liquid (electrolyte)

Question 2

in an electrolytic cell whats positive and whats the electron flow

Answer 2

anode (positive)
power supply (-) ->cathode -> anode -> power supply (+)

Question 3

electroplating

Answer 3

uses electrolysis to coat an object w a thin layer of metal
protects against corrosion

Question 4

factors affecting amount of products formed in electrolytic cell

Answer 4

ion charge
current flowing
time current flows

Question 5

faradays first law

Answer 5

mass of metal deposited at the cathode is directly proportional to the electric charge passed through the electrolyte
q = I x t
m is directly proportional to Q

Question 6

outline steps of electroplating with tin II nitrate

Answer 6

object immersed in electrolytic solution containing ions of the metal to be plated (tin II nitrate)

sn 2+ ions -> cathode -> plated

NO3- ions ->andoe -> allowed current to pass through the cell

Question 7

faradays second law

Answer 7

the amount of substances deposited or dissolved is related to the n(e-) required in a redox reaction
Q = n)e-) x F

Question 8

secondary cells

Answer 8

rechargeable galvanic cells

Question 9

discharge vs recharge

Answer 9

chem -> electrical energy is discharging. its spontaneous. uses chem energy stored within reactants bonds.anode is negative

Question 10

role of power supply in recharge phase

Answer 10

provides V to initiate electrolytic reaction
+ terminal connected to + electrode and vice versa

Question 11

role of electrolyte in cells

Answer 11

allows flow of ions within the cell (internal circuit)
cations -> cathode

Question 12

role of separator

Answer 12

separates cathode and anode
allows flow of ions between electrodesro

Question 13

role of wire

Answer 13

allows flow of e- frm site of oxidation to reduction (anode to cathode)
aka external circuit

Question 14

conditions for recharge

Answer 14

The cell must be connected to a power supply that provides a voltage above the
required voltage.
* The products of the discharge half-reactions must remain in contact with the electrode at which they react.

Question 15

factors that decrease a cells ability to recharge

Answer 15

Side reactions reduce the efficiency of the cell by reducing the amount of useful product that can be recharged.

• High temperatures increase the possibility of side reactions.
• Low temperatures increase the possibility of crystallisation.