Redox and electrode potentials

draw a diagram of how you would measure the standard electrode potential of Fe3+

the more negative electrode potential…

is oxidised therefore the reducing agent

the more positive electrode potential…

is reduced therefore the oxidising agent

oxidising agent

gains electrons

reducing agent

loses electrons

Ecell =

more positive electrode potential - more negative electrode potential

P e N

what should be added to identify the end point of the titration between I2 and thiosulfate S2O3 2

A starch indicator is added near the end point when the iodine fades a pale yellow to emphasise it. With starch added the colour change is from blue/black to colourless

Observations during Fe2+ with MnO4 – titration

colour change from colourless to purple (Mn is in burette) vs purple to colourless (Mn is in conical flask)

electrons flow from…

half cell being oxidised (producing electrons) to half cell being reduced

advantages of hydrogen fuel cells

• less pollution and CO2

• greater efficiency

disadvantages of hydrogen fuel cells

• hydrogen is highly flammable, safety issues with storing it

• high production costs + use of toxic chemicals in production

fuel cell

reacts with oxygen to give electrical energy

maintain a constant voltage

primary cells

non-rechargeable

secondary cells

rechargeable