Electrochemistry
Chemistry Notes
GCE Study Buddy
Electrical devices and circuit symbols
Electrical devices and circuit symbols
Electrodes
Conductors and non-conductors
Electrolytes, weak-electrolyte and non-electrolyte
Electrolytes, weak-electrolyte and non-electrolyte
Non-electrolytes | Weak electrolytes | Strong electrolytes |
Organic liquids or solutions | Weak acids and alkalis | Strong acids, alkalis and salt solutions |
Ethanol, C2H5OH (l) | Limewater, Ca(OH)2 (aq) | Aqueous sulphuric acid, H2SO4 (aq) |
Tetrachloromethane, CCl4 (l) | Ammonia solution, NH3 (aq) | Aqueous nitric acid, HNO3 (aq) |
Trichloromethane, CHCl3 (l) | Aqueous ethanoic acid CH3COOH (aq) | Aqueous hydrochloric acid, HCl (aq) |
Pure water, H20 (l) | Aqueous sulphurous acid, H2SO3 (aq) | Aqueous potassium hydroxide, KOH (aq) |
Sugar solution, C12H22O11 (aq) | Aqueous carbonic acid, H2CO3 (aq) | Aqueous sodium hydroxide, NaOH (aq) |
Molten sulphur, S (l) | | Copper(II) sulphate solution, CuSO4 (aq) |
Distinguishing electrolytes
Electrolysis: decomposing using passage of electricity
Electrolysis
Electrolysis
Electrolysis of Lead (II) Bromide (molten only)
At the anode
At the cathode
Electrolysis of concentrated sodium chloride solution (brine)
Electrolysis of concentrated sodium chloride solution (brine)
As the hydrogen ions and chloride ions are discharged, sodium ions and hydroxide ions remain in the solution -> becomes sodium hydroxide
Electrolysis of aqueous sulphuric acid
Electrolysis of aqueous sulphuric acid
Preferential discharge
Cations | Anions |
K+ (aq) | SO42- (aq) |
Na+ (aq) | NO3- (aq) |
Ca2+ (aq) | Cl- (aq) |
Mg2+ (aq) | Br- (aq) |
Zn2+ (aq) | I- (aq) |
Fe2 (aq) | OH- (aq) |
Pb2+ (aq) | |
H+ (aq) | |
Cu2+ (aq) | |
Ag+ (aq) | |
Difficulty of discharge decreases
Factors affecting electrolysis
Concentration
| Anode | Cathode |
Dilute hydrochloric acid | Oxygen gas | Hydrogen gas |
Concentrated hydrochloric acid | Chlorine gas | Hydrogen gas |
Concentration
Type of electrode
| Anode | Cathode |
Copper(II) sulphate with carbon electrode | Oxygen gas | Copper deposited |
Copper(II) sulphate with copper electrode | Copper anode dissolves | Copper deposited |
Industrial applications: purification of copper
Industrial applications: manufacture of sodium hydroxide
Industrial applications: electroplating
Industrial applications: electroplating
Metal | Object |
Zinc (galvanise) | Dustbins, buckets |
Chromium | Car bumpers, bicycle handle bars |
Silver | Watches, bracelets |
Copper | Saucepans |
Nickel (EPNS) | Cutlery (electroplated nickel steel_ |
Gold | Jewellery, watches |
Cells and batteries
Cells and batteries
Reactivity series
Dry cells
Dry cells
Dry cells