14.4 electrode potentials

Question 1

how is an electrochemical cell set up?

Answer 1

2 half-cells connected with salt bridge

Question 2

what is the role of the salt bridge?

Answer 2

connects circuit so free flowing ions could conduct charge

Question 3

what is the salt bridge usually made of?

Answer 3

filter paper soaked in KNO3, must be unreactive with electrodes & solutions

Question 4

what would be produced when half-cells are connected into a circuit?

Answer 4

small voltage

Question 5

what electrode should be used if a system doesn’t include metals?

Answer 5

Pt electrode as conducting surface for e- transfer
- unreactive & conducts electricity

Question 6

when should a solid vertical line be used in a cell diagram?

Answer 6

half equations include different physical states

Question 7

where is the most oxidised form drawn on a cell diagram?

Answer 7

next to salt-bridge

Question 8

where is the more positive half-cell written?

Answer 8

right hand side

Question 9

what is the equation for the standard hydrogen electrode?

Answer 9

H2(g) <-> 2H+ (aq) + 2e-

Question 10

what are the components (standard conditions) of a standard hydrogen electrode?

Answer 10

H2 gas at 100kPa
solution of 1 mol dm-3 H+ (usually HCl)
298 K

Question 11

why are standard conditions needed?

Answer 11

position of redox equilibrium changes with conditions

Question 12

give the definition of standard electrode potential.

Answer 12

the potential difference measured when a electrode system is connected to a hydrogen electrode system under standard conditions

Question 13

what are the standard conditions for all electrodes?

Answer 13

ion solutions at 1 mol dm-3
298 K
100 kPa
no current flowing