C4/Chemical Changes Flashcards
oxidation is the loss of gain of oxygen?
gain
cooper+oxygen—>copper oxide.
what has been oxidised?
copper
what type of ions do metals make?
positive
what happens when a more reactive metal is placed into a solution of a less reactive metal?
a displacement reaction
which metal is more reactive?
lithium, sodium or potassium
potassium
which metal forms it’s ion easier?
lithium, sodium or potassium
potassium
what is an ore?
a rock that contains metal compounds
name 2 ways to extract metals from their ores
heating with carbon
electrolysis
what is reduction in terms of oxygen?
losing oxygen
copper oxide+carbon—> copper+carbon dioxide
what has been reduced and what has been oxidised?
copper oxide reduced to copper
carbon oxidised to carbon dioxide
why can copper be extracted from its ore by heating it with carbon but you need to use electrolysis to extract aluminium from its ore?
copper is less reactive than carbon so the carbon will reduce the copper.
aluminium is more reactive than carbon so no reaction will occur if heated with carbon.
what does OILRIG stand for?
oxidation is lost reduction is gain
what is oxidation in terms of electrons?
loss of electrons
what is reduction in terms of electrons?
gaining electrons
what name is given to a reaction where oxidation and reduction both take place?
REDOX
what type of salts does hydrochloric acid make?
chlorides
what types of salts does sulphuric acid make?
sulphites
what type of salts does nitric acid make?
nitrates
what pH are acidic substances?
0-6
what pH are alkaline substances?
8-14
what pH are neutral substances?
7
what type of acid is fully ionised in water?
strong
give 3 examples of strong acids
hydrochloric, sulphuric and nitric
ethanoic, citric and carbonic are all examples of what type of acid?
weak
what happens to the ions in an ionic substance when they are dissolved in solution?
the ions dissociate(are free to move)
what name is given to the liquids that ionic substances are dissolved in before electrolysis can happen?
electrolytes
what is the name of the negative electrode?
cathode
what is the name of the positive electrode?
an ode
which electrode are negative ions attracted towards?
annode, positive electrode
what does the world molten mean?
a melted substance
what is produced at each electrode during the electrolysis of molten lead bromide?
cathode will produce lead
annode will produce bromine
when is electrolysis better/more cost effective at extracting metals from their ores than reduction with carbon?
when the metal is more reactive than carbon
during the electrolysis of the aluminium ore bauxite, why is the bauxite dissolved in cryolite?
lowers the melting point of bauxite
more cost effective
uses less energy
why does the annode need to be resolved every few weeks during the electrolysis of bauxite?
the annode gets worn away as carbon dioxide is made from the oxygen in bauxite and the carbon in the annode
what is produced at the negative electrode if the metal in solution is more reactive than hydrogen?
hydrogen
what is produced at the positive electrode if the ionic substance is dissolved in water?
oxygen unless a halide ion (group7) is in the ionic compound
what is produced at each electrode during the electrolysis of the following solutions dissolved in water: sodium chloride?
cathode: hydrogen
annode: oxygen
