Electrode Potentials

Question 1

what is a type of electrochemical cell?

Answer 1

voltaic cell

Question 2

what is a voltaic cell? and where does it take place?

Answer 2

converts chemical energy into electrical energy
- this takes place in modern cells and batteries

Question 3

what is needed to make a voltaic cell?

Answer 3

• movement of electrons which results in electrical energy
• so chemical reactions which transfer electrons from one species to another (redox reactions)

Question 4

how are electrochemical cells constructed?

Answer 4

• a half cells which contains chemical species present in a redox half equation

Question 5

how is a voltaic cell constructed?

Answer 5

• can be made by connecting two different half cells
• allows electrons to flow

Question 6

how must the half cells be kept?

Answer 6

apart

Question 7

what happens if the half cells mix?

Answer 7

• if mixed, electrons flow in an uncontrolled way and heat energy would be released instead of electrical energy

Question 8

what are the two types of half cells?

Answer 8

• metal/metal ion half cells
• ion/ion half cells

Question 9

what does a metal/metal ion half cell consist of?

Answer 9

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

Question 10

what does the vertical line of a metal/metal ion half cell show?

Answer 10

• phase boundary which is between the metal and aqueous solution
• at the phase boundary, where metal is in contact with ions, an equilibrium is set up

Question 11

in the equilibrium of a metal/metal ion how is it written?

Answer 11

• the forward reaction shows reduction and the reverse reaction shows oxidation

Question 12

what happens in an isolated half cell?

Answer 12

• there is no net transfer of electrons either into or out of the metal

Question 13

when the two half-cells are connected, what determines the direction of electron flow?

Answer 13

• direction of electron flow depends on the tendency of each electrode to lose electrons (their reactivity)

Question 14

what does an ion/ion half cell consist of?

Answer 14

• consists of ions of the same element in different oxidation states

Question 15

what is an example of the ion/ion half cell?

Answer 15

Fe3+(aq) + e- <–> Fe2+(aq)

Question 16

what does an ion/ion half cell require, and why?

Answer 16

• since there is no metal to transport electrons in or out of the half cell
• an inert metal electrode made of platinum is used

Question 17

how do you check if a reaction is feasible using cell potentials?

Answer 17

• in equation check which is being oxidised and which is being reduced
• look at electrochemical cell and the more negative one should be oxidised
• if oxidation is the same in reaction dnd electrochemical series then the reaction is feasible