Topic 3- Part two Electrolysis + Flashcards
What are electrolytes?
Ionic compounds in molten or dissolved state
What is electrolysis?
A process that uses electrcal energy from a direct current supply to decompose electrolytes
What happens to molten ions in electrolysis?
1)Positive attracted to negative cathode
2)Negative attracted to positive anode
Why do electolytes migrate in electrolysis?
-Molten fee movement
-Strong Electrostatic force of attraction between cathode/anode
What happens to ions at anode/ cathode
-Ions are discharged
-Produces elements
What is different when electrolyte is in dissolved state/ ionic solution?
-H2O ions will also be present in the solution
-H+
-OH-
water dissolves the ions so they can freely move
What is produced at the electrodes?
The least/ less reactive ion
What is produced at the anode if OH is less reactive than the electrolyte?
-Oxygen
hydroxide gives of oxygen (oxygen is less reactive than hydrogen)
Reactivity series with hydrogen
cathode
1) K
2) Na
3) L
4) Ca
5) Mg
4) Al
6) C
7) Zn
8) Fe
9) Sn
10) Fe
11) H
12) Cu
13) Ag
12) Au
13) Pt
What ions at the anode stay in solution and oxygen is discharged instead?
1) Carbonate
2) Nitrate
3) Sulphate
Which Ions are discharged and OH- remains in solution?
1) Chloride
2) Bromide
3) Iodide
Products of molten electrolysis?
The ions become thier elements at electrodes as they loose/gain electrons
Write a half equation?
-Shows change in number of electrons in the ions
-E.g Na <— Na+ + e-
Al<— Al3+ + 3e-
What reaction at cathode?
reduction
What reaction at anode?
Oxidation
What is a reduction reaction?
Gains electrons
What is an oxidation reaction?
Looses electrons
Electrolysis of copper sulphate with copper electrodes to purify copper (anode)?
-Anode is impure copper
-Cathode is pure copper
-Copper sulfate solution
- Copper in solution is attracted to cathode + is discharged as pure copper
-
Copper from anode + more reactive metals replace Copper in solution
-Less reactive than copper become sludge at bottom
cathode increases in mass, anode looses mass
Electrolysis of copper sulphate with inert electrodes?
1) Copper + Oxygen produced
2) Leaves H2SO4
How to use electrolysis for coating metals?
I THINK:
same as copper purification:
1) Metal to coat as cathode
2) Coating metal as solution
3) Same metal as anode
1) Solution attracted to cathode + coats it
2) Anode metal replaces in solution
Batteries
