C3.3- Electrolytic Processes Flashcards
What are cathodes and what do the attract?
Cathodes are negative electrodes which attract positive cations.
What are anodes and what do they attract?
Anodes are positive electrodes which attract negative anions.
What happens at the cathode?
Electrons are transferred from the cathode to the positive ions- reduction.
What happens at the anode?
The negative ions lose electrons to the anode. This is called oxidation.
How is sodium is used?
In street lamps- the vapour gives out bright yellow light when electricity passes through it.
Coolant in nuclear reactors- liquid sodium has high conductivity and transfers heat efficiently from the reactor core to the water.
What happens during the electrolysis of sodium chloride?
The positive sodium ions gain electrons at the cathode and the chlorine ions lose electrons at the anode.
What are the products of the electrolysis of sodium chloride solution?
Sodium hydroxide, chlorine and hydrogen. This is because chlorine and hydrogen are more easily discharged at the electrodes so a sodium hydroxide solution forms.
What is formed in the electrolysis of copper chloride solution?
Copper at the cathode, chlorine at the anode. Other ions are left in the solution.
What are he products of the electrolysis of copper sulphate solution?
Hydroxide ions at the anode, copper at the cathode and the other ions are left in the solution. The hydroxide ions become water and oxygen when discharged.
What are the products of the electrolysis of sodium sulphate solution?
Hydrogen at the cathode and oxygen at the anode. Sodium ions remain in the solution.
What are the products of the electrolysis of lead bromide?
Anode- bromine (brown vapour)
Cathode- molten lead.
How is copper extracted from its ore?
The ore is heated with carbon (smelting), producing an umpire product of copper and other elements and compounds.
How is the impure copper product refined?
To purify the copper mixture is is electrolysed. The impure copper is used as an anode and the cathode is thin sheet of pure copper. The electrolyte is copper sulphate solution. The copper atoms in the anode lose two electrons and become copper ions, which dissolve and migrate to the cathode. Cathode increases in mass.
What is electroplating?
Depositing a thin layer of one metal on the surface of another.
How does electroplating work?
The cathode is the object to be plated and the anode is the pure metal. As the atoms at the anode lose electrons and become atoms they are attracted to the cathode, coating it. To create a thicker layer the electrolysis goes on for longer.
