CC11 - extracting Metals & CC12 - reversible reactions and equilibria Flashcards
What is oxidation
When oxygen is added to a substance (loss of electrons)
What is reduction
When oxygen is removed from a substance (gain of electrons)
What is a redox reaction
A reaction where both oxidation and reduction occur
What is a sign that a reaction has occurred
Effervescence (more = higher reactivity)
What gas is produced when metals are reacted with acid
Hydrogen
What is the test for hydrogen
Hold a lit splint to the gas, if hydrogen is present there will be a squeaky pop
Word equation for metals reacting with acid
Metal + acid —> salt + hydrogen
Word equation for metal reacting with water
Metal + water —> metal hydroxide + hydrogen
Example of a redox reaction
Displacement reactions
What occurs during a displacement reaction
A more reactive element reacts to take the place of a less reactive element in a compound
Redox in metal displacement reactions
More reactive metal = lose electrons (oxidation)
Less reactive metal = gain electrons (reduction)
What happens when a reactive metal is put in a solution of a less reactive metal salt
The reactive metal will react to take the place of the less reactive metal in the salt compund
What happens if a less reactive metal is added to a solution of a more reactive metal salt
Nothing, a less reactive metal cannot take the place of a more reactive metal
What happens if a metal is added to a solution of a metal salt of the same metal
Nothing, the same metal cannot displace itself
What is an ore
A rock that contains a compound with enough metal to make extracting the metal economically viable
What is economically viable
It make sense financially eg. Profit can be made
Copper ore
Malachite
Aluminium ore
Bauxite
Iron ore
Hematite
What does the method used to extract the metal from its ore depend on
How reactive it is
Why are gold and platinum present in the earth as uncombined elements
They are very unreactive
What does extracting metals by reduction using carbon depend on
It only works if the metal is less reactive than carbon
Word equation for extraction using carbon
Metal oxide + carbon —> metal + carbon dioxide
How are metals that are more reactive than carbon extracted from their ores
Electrolysis
Why is electrolysis only used for metals more reactive than carbon
It is more expensive to run as it involves large amounts of electricity
It also costs a lot to melt or dissolve the metal ore so it conducts (ions can move)
Why can carbon only be used to extract metals less reactive than itself
Carbon can only take the oxygen (displace) from elements less reactive than iself
Why must ores be molten or dissolved to under go electrolysis
So that the ions can move to the electrodes once electric current is passed through
Where is the metal discharged in electrolysis
Cathode (negative)