56638
Description
Mind Map by Alice Clayden, updated more than 1 year ago
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Created by Alice Clayden
over 11 years ago
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Topic 3: Electrolytic
Processes
- Molten/ aqueous ionic substances (e.g copper
chloride(aq))- charged ions migrate to the electrode
of opposite charge and solution is separated
- At anode (+) - negative ions (anions) lose
electrons and are oxidised, they become
atoms again. e.g. chloride ions into chlorine.
- At cathode (-) - positive ions
(cations) gain electrons and
are reduced, they become
atoms again. e.g. copper
ions turn to solid copper.
- Half equations show what
happens at the electrodes.
e.g. anode- 2Cl- > Cl2 +
2e-, cathode - Cu+ + e- >
Cu
- At anode (+) - negative ions (anions) lose
electrons and are oxidised, they become
atoms again. e.g. chloride ions into chlorine.
- Electrolysis of sodium chloride: (salt water/ brine)
electrolyte is water- ions present are
Na+, Cl-, H+, OH-
- Sodium (Na+) and Hydrogen (H+) ions migrate
towards the cathode. H gas is given off as H+ ions
gain electrons (reduction). Sodium stays in solution.
- Hydrogen used for making ammonia and margarine
- Hydrogen used for making ammonia and margarine
- Hydroxide (OH-) and Chloride
(Cl-) ions migrate to the anode. Cl
gas given off as Cl- ions lose
electrons (oxidation). Hydroxide
stays in solution
- Chlorine used for
making bleaches,
disinfectants, paints
and plastics
- Chlorine used for
making bleaches,
disinfectants, paints
and plastics
- Sodium
hydroxide
solution is
produced
(NaOH)- used
in making
soap, paper
and synthetic
fibres
- Sodium (Na+) and Hydrogen (H+) ions migrate
towards the cathode. H gas is given off as H+ ions
gain electrons (reduction). Sodium stays in solution.
- Sodium metal can be obtained if
molten sodium chloride is
electrolysed- Na at the cathode, Cl at
the anode
- uses of sodium- nuclear reactants as a
coolant and in street lights to make
them yellow
- Na+ + e- > Na
- uses of sodium- nuclear reactants as a
coolant and in street lights to make
them yellow
- Electroplating
- Coating an object e.g. silver
cutlery with a thin layer of
metal by electrolysis
- Why do this? used to make a cheaper
metal object e.g. stainless steel cutlery
look more attractive and shiny by
coating in silver.
- Jewellery is often gold plated, and
tins and car wheels are plated to
protect them from corrosion
- Jewellery is often gold plated, and
tins and car wheels are plated to
protect them from corrosion
- the object being plated is
used as the cathode and
the metal being used is the
anode
- Positive metal migrates
over and is reduced,
forms a solid mteal
layer on the object
- the electrolyte has to contain the relevant metal
ions e.g. copper sulfate to coat a nail in copper
- the electrolyte has to contain the relevant metal
ions e.g. copper sulfate to coat a nail in copper
- Positive metal migrates
over and is reduced,
forms a solid mteal
layer on the object
- Coating an object e.g. silver
cutlery with a thin layer of
metal by electrolysis
- Purification of copper
- Active electrodes used- anode is impure copper, cathode is
a very small strip of pure copper
- positively charged copper ions (Cu2+) move from the
anode to the cathode where they reduce back to
copper atoms and they form solid pure copper.
- impurities are not attracted to the cathode and so are left behind and fall
to the bottom of the electrolyte. It is called sludge and has some uses
- it may contain valuable
metallic elements e.g. gold,
silver, platinum
- it may contain valuable
metallic elements e.g. gold,
silver, platinum
- impurities are not attracted to the cathode and so are left behind and fall
to the bottom of the electrolyte. It is called sludge and has some uses
- copper sulfate solution used as electrolyte
- Active electrodes used- anode is impure copper, cathode is
a very small strip of pure copper
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