CC10a Electrolysis
Electrolyte -
substance that conducts electric current as a result of a dissociation into positively and negatively charged
particles called ions, which migrate toward and ordinarily are discharged at the negative and positive
terminals (cathode and anode) of an electric circuit
Electrolysis -
Process by which ionic substances are decomposed (broken down) into simpler substances when an electric
current is passed through them. Electricity is the flow of electrons or ions.
Movement of ions during electrolysis -
A positive ion (CATION because it’s PAWsitive) will move to the negative electrode (cathode) to gain
electrons and the negative ion (anion) will move to the positive electrode (anode) to lose electrons.
Oxidation and Reduction -
At the CATHODE the cations gain electrons which means REDUCTION takes place at the cathode (negative
electrode) and at the ANODE, the anions lose electrons which means OXIDATION takes place at the anode
(positive electrode).
O - oxidation P - Positive
I - is A - Anode
L - loss N - Negative
I - is
R - reduction C - Cathode
I - is
G - gain
CC10b Products of Electrolysis
What is produced at the Cathode and Anode -
IN SOLUTION :
Anode Cathode
Produces oxygen from OH- ions unless a halide ion Produces hydrogen unless metal is LESS reactive
is present. than hydrogen. E.G :
If higher in reactivity series than hydrogen like Iron,
IF HALIDE ION IS PRESENT : tin, etc then Hydrogen is produced. If lower than
Bromide (__)produces Bromine (__) hydrogen like copper, silver and gold, the actual
Chloride (__) produces Chlorine (__) metal is formed.
Iode (__) produces Iodine (__) Reactivity series :
Iron
IF NO HALIDE ION : Tin
Oxygen is produced from the OH- ions that are Lead
present in solution. Hydrogen
Copper
Silver
Gold
E.g Copper Sulfate.
In this reaction copper would go to the cathode because copper is a cation as it has a +2 charge.As it’s in a
solution OH- and H+ ions are also present. Since hydrogen (H+) has a positive charge it will also go to the
cathode with the copper, but only one thing can be produced. So if we use the rules, we can see that copper
is LESS reactive than hydrogen and therefore Copper is produced instead of hydrogen. Sulfate and
hydroxide (OH-) ions will go to the anode since they have a negative charge and the anode is positive. At the
anode, if we use the rules we will know that oxygen will be produced from the OH- ions as there is no halide
present. Therefore, at the end of the electrolysis you will have copper and oxygen produced.
, CC11a Reactivity
Displacement Reactions -
In a displacement reaction, a more reactive metal will take over the place of a less
reactive metal in a reaction. For example:
Ca+ZnCl -> CaCl+Zn
In this reaction Zinc is being displaced as it goes from Zinc chloride to just zinc. This
happens because Calcium is more reactive and it takes over Zinc's place.
You can tell how reactive a metal is by seeing how it reacts with oxygen, water and acid.
This is because the more reactions you get and the stronger they are, the higher up
they are in the reactivity series. If there’s no reaction like with Gold, then they have low
reactivity as nothing changes or affects them.
CC11b Ores
Ore -
Ore is natural rock or sediment that contains one or more valuable minerals, typically containing metals, that
can be mined, treated and sold at a profit.
Metals that are found in ‘native state; are not ores as they are found uncombined to the earth's crust due to
their low reactivity. They are naturally in their native state. ( Uncombined element)
Some native state metals are : gold, silver and platinum.
Extraction -
Some metals are extracted from their ores by heating with CARBON because they are less reactive than
carbon so when heated, carbon would displace them in the reaction and leave them uncombined.
Other metals that are more reactive than carbon need to be extracted from their ores by electrolysis because
carbon wouldn’t be able to displace them when heated together.
Electrolyte -
substance that conducts electric current as a result of a dissociation into positively and negatively charged
particles called ions, which migrate toward and ordinarily are discharged at the negative and positive
terminals (cathode and anode) of an electric circuit
Electrolysis -
Process by which ionic substances are decomposed (broken down) into simpler substances when an electric
current is passed through them. Electricity is the flow of electrons or ions.
Movement of ions during electrolysis -
A positive ion (CATION because it’s PAWsitive) will move to the negative electrode (cathode) to gain
electrons and the negative ion (anion) will move to the positive electrode (anode) to lose electrons.
Oxidation and Reduction -
At the CATHODE the cations gain electrons which means REDUCTION takes place at the cathode (negative
electrode) and at the ANODE, the anions lose electrons which means OXIDATION takes place at the anode
(positive electrode).
O - oxidation P - Positive
I - is A - Anode
L - loss N - Negative
I - is
R - reduction C - Cathode
I - is
G - gain
CC10b Products of Electrolysis
What is produced at the Cathode and Anode -
IN SOLUTION :
Anode Cathode
Produces oxygen from OH- ions unless a halide ion Produces hydrogen unless metal is LESS reactive
is present. than hydrogen. E.G :
If higher in reactivity series than hydrogen like Iron,
IF HALIDE ION IS PRESENT : tin, etc then Hydrogen is produced. If lower than
Bromide (__)produces Bromine (__) hydrogen like copper, silver and gold, the actual
Chloride (__) produces Chlorine (__) metal is formed.
Iode (__) produces Iodine (__) Reactivity series :
Iron
IF NO HALIDE ION : Tin
Oxygen is produced from the OH- ions that are Lead
present in solution. Hydrogen
Copper
Silver
Gold
E.g Copper Sulfate.
In this reaction copper would go to the cathode because copper is a cation as it has a +2 charge.As it’s in a
solution OH- and H+ ions are also present. Since hydrogen (H+) has a positive charge it will also go to the
cathode with the copper, but only one thing can be produced. So if we use the rules, we can see that copper
is LESS reactive than hydrogen and therefore Copper is produced instead of hydrogen. Sulfate and
hydroxide (OH-) ions will go to the anode since they have a negative charge and the anode is positive. At the
anode, if we use the rules we will know that oxygen will be produced from the OH- ions as there is no halide
present. Therefore, at the end of the electrolysis you will have copper and oxygen produced.
, CC11a Reactivity
Displacement Reactions -
In a displacement reaction, a more reactive metal will take over the place of a less
reactive metal in a reaction. For example:
Ca+ZnCl -> CaCl+Zn
In this reaction Zinc is being displaced as it goes from Zinc chloride to just zinc. This
happens because Calcium is more reactive and it takes over Zinc's place.
You can tell how reactive a metal is by seeing how it reacts with oxygen, water and acid.
This is because the more reactions you get and the stronger they are, the higher up
they are in the reactivity series. If there’s no reaction like with Gold, then they have low
reactivity as nothing changes or affects them.
CC11b Ores
Ore -
Ore is natural rock or sediment that contains one or more valuable minerals, typically containing metals, that
can be mined, treated and sold at a profit.
Metals that are found in ‘native state; are not ores as they are found uncombined to the earth's crust due to
their low reactivity. They are naturally in their native state. ( Uncombined element)
Some native state metals are : gold, silver and platinum.
Extraction -
Some metals are extracted from their ores by heating with CARBON because they are less reactive than
carbon so when heated, carbon would displace them in the reaction and leave them uncombined.
Other metals that are more reactive than carbon need to be extracted from their ores by electrolysis because
carbon wouldn’t be able to displace them when heated together.
