cells and electrolysis Flashcards
(28 cards)
Metals that are hard to oxidise
gold and silver
What do anodes and cathodes attract
anode attract anions
Cathodes attract cations
what particles react in metals
Ions and electrons
what does redox stand for
reduction oxidation.
What does reduction mean
Reduction means electrons are gained
what does oxidation mean
Oxidation means electrons are lost.
Silver nitrate + copper =
copper nitrate + silver
How is solid copper oxidised to copper ions
Solid copper is oxidised to copper ions by losing 2 electrons
how are silver ions reduced to solid silver
Silver ions are reduced to solid silver by gaining 1 electron
What happens when magnesium reacts with oxygen in the air
2Mg(s) + O2(g) ———> 2MgO(s)
The magnesium atom LOSES ELECTRONS to become a magnesium ion
What happens when magnesium reacts with chlorine
So, when magnesium takes part in an oxidation reaction it loses electrons.
When magnesium reacts with chlorine it also loses electrons.
Mg(s) + Cl2(g) ———> MgCl2(s)
what happens when lead is extracted from lead (II) oxide
When lead is extracted from lead (II) oxide , carbon is used to remove the oxygen
2PbO(s) + C(s) ———> 2Pb(s) + CO2(g)
The oxygen has been removed from the lead (II) oxide
The lead (II) oxide has been REDUCED
How does lead (II) oxide form lead)
In the compound lead (II) oxide the lead is an ion, Pb2+
In order to form lead the Pb2+ ion has to GAIN 2 electrons
We can write this as follows:
Pb2+(s) + 2e- ——> Pb(s)
what is redox
You may have noticed that when the magnesium loses its electrons they are gained by the oxygen
Oxidation (loss of electrons) and reduction (gain of electrons) happen simultaneously.
We call these REDOX reactions
Redox simplified
The chemical whichgainselectrons isreduced(reducesits valency) and is called theoxidisingagent.
The chemical whichloseselectrons, isoxidised(increasesits valency) and is called thereducingagent.
electrolysis
Passing an electric current through ionic substances that are molten
or in aqueous solution, breaks them down into elements.
Electrolyte
Passing an electric current through ionic substances that are molten
or in aqueous solution, breaks them down into elements.
The process is known as ELECTROLYSIS
What happens during electrolysis
Positively charged ions move to the negative electrode - CATHODE
Negatively charged ions move to the positive electrode - ANODE
DO SOLID IONIC COMPOUNDS CONDUCT ELECTRICITY
WHEN SOLID, THE IONS
ARE NOT FREE TO MOVE
NO CONDUCTION
OF ELECTRICITY
DO MOLTEN IONIC COMPOUNDS CONDUCT ELECTRICITY
WHEN MOLTEN, THE IONS
ARE FREE TO MOVE
ELECTRICITY IS
CONDUCTED
DO AQUEOUS SOLUTIONS OF IONIC COMPOUNDS CONDUCT ELECTRICITY
WHEN DISSOLVED IN WATER, THE IONS ARE. FREE TO MOVE ELECTRICITY IS CONDUCTED
DOES SOLID SODIUM CHLORIDE CONDUCT ELECTRICITY
SOLID SODIUM CHLORIDE DOES NOT
CONDUCT ELECTRICITY BECAUSE
THE IONS ARE NOT FREE TO MOVE
TO THE ELECTRODES
Why is aluminium used in cars
It is less dense
How are reactive metals extracted
Electrolysis
