Electrolysis

Question 1

Electrolysis

Answer 1

break down of compound into its elements using an electric current

Question 2

Electrolysis is used for

Answer 2

-Extract metals from their metal ores when the metals cannot be extracted by heating their ores with carbon
-Purify metals
-Produce non-metals such as fluorine

Question 3

Electrolyte

Answer 3

the compound that is broken down during electrolysis and it is either a molten ionic compound or a concentrated aqueous solution of ions

Question 4

Anode

Answer 4

the positive electrode

Question 5

Cathode

Answer 5

the negative electrode

Question 6

Electrolysis of molten electrolytes

Answer 6

-Cations (positively charged ions) move to the negatively charged cathode where they gain electrons
-Reduction takes place at the cathode
-If a metal is formed, a layer of metal is deposited on a cathode or it forms a molten layer in the cell
-If hydrogen gas is formed, bubbles are seen

-Anions (negatively charged ions) move to the positively charged anode where they lose electrons
-Oxidation takes place at the anode

Question 7

Electrolysis of aqueous solutions

Answer 7

-Aqueous solutions have more than one cation and anion in solution due to the presence of water
-The actual ions that are discharged during electrolysis will depend on:
1)The relative electrode potential of the ions
2)The concentration of the ions
-The positively charged cation with the most positive Eꝋ will be discharged at the cathode as this is the cation that is most easily reduced
-The negatively charged anion with the most negative Eꝋ will be discharged at the anode, as this is the anion that is most easily oxidised

Question 8

How electrode potential of ion effects electrolysis in aqueous solutions

Answer 8

-The positively charged cation with the most positive Eꝋ will be discharged at the cathode as this is the cation that is most easily reduced
-The negatively charged anion with the most negative Eꝋ will be discharged at the anode, as this is the anion that is most easily oxidised

Question 9

How concentration of ions effects electrolysis in aqueous solutions

Answer 9

Ions that are present in higher concentrations are more likely to be discharged

Question 10

Relative electrode potential of ions

Answer 10

how easily an ion is discharged during electrolysis

Question 11

The amount of substance that is formed at an electrode during electrolysis is proportional to:

Answer 11

-The amount of time where a constant current to passes
-The amount of electricity, in coulombs, that passes through the electrolyte (strength of electric current)

Question 12

Q =

Answer 12

I x t

Question 13

One faraday is

Answer 13

-the amount of electric charge carried by 1 mole of electrons or 1 mole of singly charged ions
-96 500 C mol-1

Question 14

F =

Answer 14

L x e

Question 15

Avogadro’s constant (L)

Answer 15

number of entities in one mole

Question 16

L =

Answer 16

6.02 x 10^23 mol-1

Question 17

Finding L experimentally

Answer 17

L=charge on 1 mole of electrons/charge on 1 electron

Question 18

e=

Answer 18

1.6 x 10^-19 C

Question 19

Q/F=

Answer 19

n