Electrolysis – IGCSE Exam with Complete Solutions Graded A+++ Define reduction? - Correct Answer Gain of electrons Define oxidation? - Correct Answer Loss of electrons What is electrolysis? - Correct Answer • the breakdown of an ionic compound, • in a molten or in aqueous solution, • by the passage of electricity What is an electrolyte? - Correct Answer o ionic compound in
- molten or dissolved solution that
- conducts the electricity.
Liquids that are good conductors of electricity Define a conductor? - Correct Answer A material that allows heat and electricity to pass through it.Define an insulator? - Correct Answer A material that does not allow heat or electrons to move through it easily.Define molten? - Correct Answer melted by heat During electrolysis what do you understand by the term 'discharge'? - Correct Answer loses its charge, becomes neutral inert substance is ........ - Correct Answer unreactive non-electrolytes are ...... - Correct Answer Liquids that do not conduct electricity 1 / 3
What are electrodes? - Correct Answer A graphite (inert) or metal strip that conducts electricity.The cathode is the .......PANIC - Correct Answer o negative electrode of an
- electrolysis cell.
- electrolysis cell.
- attracted to the anode.
- attracted to the cathode.
The anode is the ........PANIC - Correct Answer o positive electrode of an
An anion is .......... - Correct Answer o negatively charged ion which is
A cation is ........ - Correct Answer o positively charged ion which is
What is electroplating? - Correct Answer An electrolytic process in which:
- metal ions are reduced and the
- metal atoms are deposited on a surface
Which cation (metal or hydrogen) gets discharged during electrolysis of an aqueous solution? - Correct Answer the least reactive Which anion (OH- or halide) gets discharged during electrolysis of an aqueous solution? - Correct Answer usually the halide ion (unless very dilute) 2 / 3
What is a Faraday? - Correct Answer the total charge of one mole of electrons, 96500 Coulombs What forms at the cathode? - Correct Answer either a metal or hydrogen What forms at the anode - Correct Answer a non metal other than hydrogen What is brine - Correct Answer Concentrated sodium chloride solution Why do covalent compounds (e.g H₂O) not conduct electricity? - Correct Answer They do not have free electrons - the electrons are shared in a covalent bond.Why do ionic compounds only conduct when molten or aqueous? - Correct Answer Ions are fixed when ionic compounds are solid, meaning they can't move so they can't conduct electricity.When the compounds are molten or in aqueous solution, the ions (that are electrically charged) are able to move and carry charge.To which electrodes do the lead and bromide ions go during the electrolysis of PbBr2 - Correct Answer Lead is positively charged and moves to the negative electrode (cathode).Bromine is negatively charged and move to the positive electrode (anode).Does oxidation occur at the anode or cathode? - Correct Answer Oxidation occurs at the anode.Oxidation is the loss of electrons.Does reduction occur at the anode or cathode? - Correct Answer Reduction occurs at the cathode.Reduction is the gain of electrons.Why is a mixture of aluminium oxide and cryolite used, rather than aluminium oxide alone? - Correct Answer Cryolite lowers the melting point and reduces some of the energy costs involved in extracting aluminium oxide.
- / 3