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Why does the surface of the iron in the middle of water droplet serves as the anode?
• Anode is area where electron is ………………………………• Atom ……………………here ……………………………
electron to form
…………………………..
• Fe Fe 2+ + 2e
Write half equation for the reaction at (i) above
The electrons released by the iron flows to the edge of the water where there is
plenty of dissolved oxygen. Why does the iron surface here serve as the cathode?• Cathode is area where electron is ………………………………• ……………………………..…and ………………………. here …………….. electron to
form ………………………
• 2H2O + 4e + O2 4OH-
Write half equation for the reaction at (iii) above
• 2H2O + 4e + O2 4OH-
The iron(II) ions formed in (i) combined with the hydroxide ions
formed in (iii) to form iron(II) hydroxide. Write the equation for
the reaction here• Fe Fe 2+ + 2e
Fe 2+ +2OH- Fe(OH)2
• Fe2O3.xH2O
The iron(II) hydroxide is rapidly oxidized by air to form rust. Write
formula of rust
Draw simple diagram of mechanism of rusting
Method of metals extraction• Aluminium=electrolysis of molten
aluminium oxide
• Iron= heat iron oxide with carbon
• Copper= heat copper(II) sulphide strongly in air
• Gold= unreactive metal= obtained free
What kind of metals A) prevent rusting and B) encourage rusting
• A) metals above iron in ECS
• B) metals below iron in ECS
ECS and RS• K
• Na
• Ca
• Mg
• Al
• Zn
• Fe
• Sn
• Pb
• Cu
• Hg
• Ag
• Au
(RS) C
(RS) H
H (ECS)
Differences between electrolytic cell and voltaic/chemical cell
• Electrolytic cell• Oxidation occur at
positive electrode • because negative
ions • released electrons
here
• Chemical cell cell• Oxidation occur at
negative electrode• because metal
atom • release electrons
here
Differences between electrolytic cell and voltaic/chemical cell
• Electrolytic cell• Reduction occur at
negative electrode • because positive
ions • gain electrons here
• Chemical cell cell• Reduction occur at
positive electrode• because positive
ions • gain electrons here