M5-Electrode Potentials

Question 1

Electrode potential units

Answer 1

Volts

Question 2

Golden rule

Answer 2

The more +I’ve the value, the easier it would be for it to be reduced

Question 3

Standard electrode potential

Answer 3

The voltage measured under standard conditions
25°c
100Kpa
1moldm-3 in solutions

Question 4

What type of reactions are E

Answer 4

Equilibrium reactions always

Question 5

What inert electrodes can be used in half cells

Answer 5

Carbon or platinum

Question 6

Hydrogen half cell reaction

Answer 6

2H+ + 2e- —> H2(g)

Question 7

Ethea of hydrogen half cell

Answer 7

0v

Question 8

what is needed to measure a standard potential (diagram)

Answer 8

voltmeter connected to both electrodes
salt bridge
electrodes ( an element if a solid involved in the half cell)
reactants in each half cell
standard conditions which are 25 degrees, 1atm and 1 mol per dm3 for solutions

Question 9

which electrode is which

Answer 9

reduction is positive
oxidation is negative

Question 10

measuring the Etheta for any half cells involves what

Answer 10

connecting it with a standard hydrogen half cell

Question 11

can sulfur act as an electrode when its a solid

Answer 11

NO

Question 12

calculating Ecell

Answer 12

Ecell=Ered-Eox

Question 13

what happens to a reaction that has a more positive value

Answer 13

it moves forwards

Question 14

what happens to the oxidising power as the Etheta becomes more positive

Answer 14

increases

Question 15

what happens to the reducing power as the Etheta becomes more negative

Answer 15

increases

Question 16

what happens if the Ecell is negative

Answer 16

the reaction isnt feasible

Question 17

limitations of predictions

Answer 17

Standard conditions must be used
even if Etheta suggests the reaction is feasible, the reaction may not happen as the activation energy is too high causing the rate to be too slow (not kinetically favoured)

Question 18

what happens to equilibrium when changing concentrations in a half cell

Answer 18

position of eqm shifts
more/less reduction
E value becomes more/less positive

Question 19

primary/non rechargable cells

Answer 19

provide electrical energy until all chemicals have reacted and voltage falls

Question 20

secondary/rechargable cells

Answer 20

react to provide chemical energy, then can be reversed during charging to restore them

Question 21

fuel cells

Answer 21

use energy from reaction of a fuel with oxygen to create a voltage. must both be replaced if cell is required to carry on supplying voltage

Question 22

benefits of hydrogen fuel cells

Answer 22

no co2