Electrolysis - molten salts
Electrolytes
Electrolytes are An ionic compound occurs when a negative ion (an atom that has gained an electron) joins with a positive ion (an atom that has lost an electron). that are either:
- in the A term used to describe a liquid substance (eg rock, glass or metal) formed by heating a solid. state
- A substance is said to be dissolved when it breaks up and mixes completely with a solvent to produce a solution. in water
Under these conditions, the Electrically charged particle, formed when an atom or molecule gains or loses electrons. in electrolytes are free to move within the liquid.
The decomposition (breakdown) of a compound using an electric current. is a process in which electrical energy, from a Also called dc. An electric current that flows in one direction only. (dc) supply, decomposes (breaks down) A substance which, when molten or in solution, will conduct an electric current.. The free ions in electrolytes are attracted to the oppositely-charged A conductor used to establish electrical contact with a circuit. The electrode attached to the negative terminal of a battery is called a negative electrode, or cathode. The electrode attached to the positive terminal of a battery is the positive electrode, or anode. connected to the dc supply.
Cations
The negatively charged electrode in electrolysis is called the The negative electrode during electrolysis.. Positively charged ions are called An atom or group of atoms that have lost electrons and become positively charged. Most cations are formed from metals.. They move towards the cathode.
Anions
The positively charged electrode in electrolysis is called the The positive electrode during electrolysis.. Negatively charged ions are called An atom or group of atoms that have gained electrons and become negatively charged. Most anions are formed from non-metals.. They move towards the anode.
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Products of electrolysis
When ions reach an electrode, they gain or lose Subatomic particle, with a negative charge and a negligible mass relative to protons and neutrons.. As a result, they form atoms or A collection of two or more atoms held together by chemical bonds. of elements:
- cations gain electrons from the negatively charged cathode
- anions lose electrons at the positively charged anode
Molten lead bromide, PbBr2(l), is an electrolyte. During electrolysis:
- Pb2+ ions gain electrons at the cathode and become Pb atoms
- Br- ions lose electrons at the anode and become Br atoms, which pair up to form Br2 molecules
So lead forms at the negative electrode and bromine forms at the positive electrode.
Example
Predict the products of electrolysis of molten calcium chloride.
Calcium will form at the negative electrode because metals form there from positively charged metal ions. Chlorine will form at the positive electrode because non-metals form there from negatively charged non-metal ions.
Question
Predict the products of electrolysis of molten aluminium oxide.
Aluminium will form at the negative electrode and oxygen will form at the positive electrode.