WJEC GCE A2 Chemistry UNIT 3

standard electrode potential

• the potential difference when a half cell is connected to the hydrogen electrode at 298K, and all solutions at 1moldm-3 and all gas at 1atm

• the current when a half cell is connected to the hydrogen electrode at 298K, and all solutions at 1moldm-3 and all gas at 1atm

• the potential difference when a half cell is connected to another electrode at 298K, and all solutions at 1moldm-3 and all gas at 1atm

• the current when a half cell is connected to another electrode at 298K, and all solutions at 1moldm-3 and all gas at 1atm

colour change copper sulphate zinc redox

• blue to colourless

  red precipitate on zinc

• purple to colourless

• orange to green

• pale green to yellow

colour change permanganate to manganate

• blue to colourless

  red precipitate on zinc

• purple to colourless

• orange to green

• pale green to yellow

colour change dichromate to chromate

• blue to colourless

  red precipitate on zinc

• purple to colourless

• orange to green

• pale green to yellow

colour change fe2+ to fe3+

• blue to colourless

  red precipitate on zinc

• purple to colourless

• orange to green

• pale green to yellow

colour change thiosulphate to s4o6-

• colourless to colourless

• blue to white

• orange to yellow

• red brown to colourless

colour change cu2+ to cu+

• colourless to colourless

• blue to white

• orange to yellow

• red brown to colourless

colour change cr2o7 2- to cro4 2-

• colourless to colourless

• blue to white

• orange to yellow

• red brown to colourless

colour change i2 to 2i-

• colourless to colourless

• blue to white

• orange to yellow

• red brown to colourless

a salt bridge...

• allows the flow of ions from one solution to another while the 2 solutions are kept separate

• soaked in potassium nitrate

• allows the flow of reduction from one solution to another while the 2 solutions are kept separate

• soaked in potation bromide