electrochemistry

Question 1

what are solid ion cells?

Answer 1

consists of metal rod dipped in aqueous solution of its ions
e.g.
Cu2+ (aq) + 2e- <———> Cu(s)

Question 2

what are ion/ion half cells?

Answer 2

contains the same elements in different oxidation states
e.g. solution of Fe2+ and Fe3+, with an inert platinum electrode

Question 3

what are gas/ion half cells?

Answer 3

hydrogen gas half cell, used as the standard electrode potential
standard conditions: 1atm, 1.0 mol dm3, 298K
H2(g) and H+ (aq) with an inert platinum electrode

Question 4

what are the uses of the salt bridge?

Answer 4

to complete the circuit
to maintain the charge of the solution

Question 5

how do you calculate Ecell?

Answer 5

E(positive electrode)-E(negative electrode)

Question 6

how do you calculate Ecell?

Answer 6

E(positive electrode)-E(negative electrode)

Question 7

What are the conditions for the acids used in a hydrogen half cell (standard reference)

Answer 7

Monobasic (release 1 mol H+)
Strong (fully dissociate)

Question 8

When the hydrogen half cell is being used as a reference, where is it drawn on a diagram?

Answer 8

On the left

Question 9

What are the rules for positioning the half cells in a diagram

Answer 9

The cell with the more negative E goes on the left

Question 10

How does concentration affect Ecell

Answer 10

1. concentration of ion increases/decreases
2. position of equilibrium shifts right/left
3. electrode potential becomes less/more negative
4. Ecell (difference between half cells) decreases/increases
   example equation: e- + Li+ <—> Li

Question 11

how do you explain whether a reaction is feasible?

Answer 11

1. compare the electrode potentials
2. state which species is oxidised/reduced
3. therefore, name the stronger oxidising/reducing agent (opposites)
4. state the effect on the position of equilibrium

Question 12

why might a feasible reaction not happen?

Answer 12

concentration not 1 mol dm3
temperature too low (not enough activation energy)