3.1 redox and standard electrode potential

Question 1

the more negative the e naught value:

Answer 1

the better the species looses electrons
as it easily oxidised so the best reducing agent

Question 2

the more positive the e naught value:

Answer 2

the better the species accepts electrons so it is easily reduced and is a good oxidising agent

Question 3

How to work out feasibility of a reaction?

Answer 3

. the most negative value the equilibrium moves to the left
. then the positive moves to the right
. circle the start of the equation and these are the ones that can react

Question 4

what does salt bridge do?

Answer 4

completes circuit and provides ions

Question 5

how to calculate cell emf?

Answer 5

emf cell on right - left
note: sometimes it’s the wrong way around so you change it

Question 6

how do you lay out cell diagram?

Answer 6

put most positive on the right and it’s the same equation but the one on the left you switch the equation around (but it depends whether there’s more positive on the right)

Question 7

what is the S.H.E?

Answer 7

reference half cell to which all other half cells are compared to has a value of 0.00V

Question 8

how does the hydrogen fuel cell work?

Answer 8

• H gas fed into anode side of cell whilst oxygen fed into cathode side.
• the hydrogen gas becomes ionised
  H2 -> 2H+ + 2e-
• then at the cathode 02 + 4H+ + 4e- -> 2H20
• the electrolyte membrane only allows the passage of positive ions to the cathode and the electrons are forced to the cathode via an external circuit. This means that the electrons power the external electrical device.
• overall reaction: 2 H2 + 02 -> 2H20

Question 9

function of electrode:

Answer 9

allows transfer of electrons
platinum- inert electrode that is used to carry the charge

Question 10

what are standard electrode potential conditions?

Answer 10

298k
1atm
1moldm-3 conc

Question 11

what is the salt bridge? made of

Answer 11

a piece of filter paper soaked in potassium nitrate