Set up and half equations
What is the positive electrode called?
Anode
What are the 3 factors affecting electrolysis?
Electrochemical/Reactivity Series
Concentration of electrolyte
Type of electrodes
Name the two active electrodes
Carbon (graphite) and platinum
Ore of aluminium
Bauxite
State 5 metals that are more reactive than carbon
K
Na
Ca
Mg
Al
What states should the electrolyte be for electrolysis to take place?
Molten and aqueous
State 3 metals that are less reactive than carbon but more reactive than hydrogen, in order of its reactivity
Zn
Fe
Sn
Pb
Uses of electroplating
Prevention from corrosion and improving appearance
Why is cryolite used?
Lower melting point of electrolyte (molten Al2O3)
Increase conductivity
Reduce cost
Between Zn and Cu, which metal would be the negative electrode of an electrochemical cell?
Zn because it is more reactive
What happens when the electrolyte is solid? Why?
Nothing happens because no free moving ions
What is the product at cathode of the electrolysis of copper (II) sulfate solution?
Copper metal
To purify copper metal, which electrode should the pure copper metal be?
Cathode
Why is the anode carbons replaced from time to time?
C (s) + O2 (g) -> CO2 (g)
Advantages of fuel cell
No pollutants- only product is water
Produce more energy per gram of fuel than other fuels
High efficiency
Don't need recharging like batteries
What is the half equation at the cathode electrode of a NaCl (l) electrolyte?
Na+ + e- -> Na
Write the half equations for the electrolysis of concentrated copper (II) chloride solution with state symbol
Anode: 2Cl- (aq) -> Cl2 (g) + 2e-
Cathode: Cu2+ (aq) + 2e- -> Cu (s)
If you want to plate an object with silver, what electrolyte should you use and which electrode should the plating metal be at?
Electrolyte: Silver compound
The plating metal: anode
Half equation at anode
O2- -> O2 + 4e-
Which combination of electrochemical cell produce the higher voltage? Zinc and copper OR Magnesium and silver
Magnesium and silver
What is the half equation at the anode of the electrolysis of water?
4OH- (aq) -> O2 (g) + H2O (l) + 4e-
Write the half equations for the electrolysis of dilute copper (II) chloride solution with state symbol
Anode: 4OH- (aq) -> O2 (g) + H2O (l) + 4e-
Cathode: 2H+ (aq) + 2e- -> H2 (g)
Half equations of electroplating a spoon with copper at both anode and cathode. Include state symbols
Anode: Cu (s) -> Cu2+ (aq) + 2e- (aq)
Cathode: Cu2+ (aq) + 2e- (aq) -> Cu (s)
Half equation at cathode
Al3+ + 3e- -> Al
What is the half equation at the negative electrode of fuel cell with an acidic electrolyte?
H2 (g) -> 2H+ (aq) + 4e-