C3.4 Electrolysis

Ions in water

H+ and OH-

H+ is attracted to

Cathode

Discharge of H+

2H+ +2e- --> H2

OH- is attracted to

Anode

Discharge of OH-

4OH- --> O2 + 2H2O + 4e-

Discharged at the cathode in solution

Least reactive element

Discharged at the anode in solution

Halide ions, if present, otherwise OH-

Halide ion

a negative ion formed from a group 7 element

Test for hydrogen

Lit splint produces a squeaky pop

Metals discharged in preference to hydrogen

Copper, Silver, Gold, Platinum

Test for chlorine

Bleaches damp litmus paper

Test for oxygen

Relights a glowing splint

Electroplating

The process of depositing a thin layer of metal on an object using electrolysis.

Electroplating cathode

The object to be plated.

Electroplating anode

The metal you want to plate with

Electroplating solution

Ions of the plating metal

Purifying copper

A form of electrolysis where impure copper is the cathode and pure copper is the anode.

Cathode

Electrode at which reduction occurs

Anode

Electrode at which oxidation occurs

Electrode

A device for conducting electricity into the liquid

Cation

A positively charged ion

Anion

A negatively charged ion

Electrolyte

An ionic compound able to conduct an electric current

Reason solid ionic substance can't conduct electricity

Ions are in fixed positions

Reason molten/dissolved ionic substances can conduct electricity

Ions are free to move and carry charge

In electrolysis ions go to

Opposite charge electrode

Positive ions go to

Cathode

Negative ions go to

Anode

Discharged

Remove an electric charge by adding/removing electrons

Oxidation in terms of electrons

Loss of electrons

Reduction in terms of electrons

Gain of electrons

When a molten compound is electrolysed the metal forms

at the cathode

When a molten compound is electrolysed the non metal forms

at the anode