23.4 electrode potentials

Question 1

what does a voltaic cell do?

Answer 1

converts chemical energy into electrical energy

Question 2

what is a half-cell?

Answer 2

contains chemical species present in a redox half-equation

Question 3

how can a voltaic cell be made?

Answer 3

connecting together two different half-cells which allows electrons to flow

Question 4

what does the simplest half-cell contain?

Answer 4

a metal rod dipped into a solution of its aqueous metal ion

Question 5

how is a metal/metal ion half-cell represented?

Answer 5

using a vertical line for the phase boundary between the aq solution and the metal

Question 6

what is formed at the phase boundary?

Answer 6

equilibrium
forward reaction shows reduction and reverse shows oxidation

Question 7

what is an ion/ion half-cell?

Answer 7

ions of the same element in different oxidation states

Question 8

what isn’t present in an ion/ion half-cell?

Answer 8

no metal to transport electrons into or out of half-cell so an inert metal electrode is made using platinum

Question 9

how do you know which electrode has a greater tendency to gain or lose electrons?

Answer 9

in a cell with two metal/metal ion half-cells connected, the more reactive metal releases electrons more readily and is oxidised

Question 10

what is the negative electrode?

Answer 10

electrode with more reactive metal loses electrons and is oxidised

Question 11

what is the positive electrode?

Answer 11

electrode with less reactive metal gains electrons and is reduced

Question 12

define standard electrode potential

Answer 12

tendency to be reduced and gain electrons

Question 13

what is the standard that is chosen and used as a comparison?

Answer 13

half-cell containing hydrogen gas and a solution containing H+ ions
inert platinum electrode is used to allow electrons into and out of the cell

Question 14

what are the standard conditions used to measure standard electrode potential?

Answer 14

solutions have concentration of 1
298 K 25 degrees
100 kPa

Question 15

what is the standard electrode potential of a standard hydrogen electrode?

Answer 15

0V

Question 16

how do you manage a standard electrode potential?

Answer 16

half cell is connected to a standard hydrogen electrode
two electrodes are connected by a wire to allow a controlled flow of electrons
two solutions are connected with a salt bridge

Question 17

what does a salt bridge do?

Answer 17

allows ions to flow

Question 18

what is a salt bridge usually made up of?

Answer 18

concentrated solution of an electrolyte that doesn’t react with either solution

Question 19

what is the forward reaction in the equilibrium for a redox system?

Answer 19

reduction

Question 20

the more negative a E value…

Answer 20

the greater the tendency to LOSE electrons and undergo OXIDATION

Question 21

the more positive the E value…

Answer 21

the greater the tendency to GAIN electrons and undergo REDUCTION

Question 22

how do you calculate standard cell potentials?

Answer 22

Standard potential from positive electrode - standard potential from negative electrode