Electrochemistry

Question 1

example of a rechargeable cell

Answer 1

lithium ion batteries

Question 1

EMF = ?

Answer 1

EMF = E reduced - E oxidised

Question 2

is a positive or negative EMF value feasible under standard conditions?

Answer 2

a positive EMF value is feasible under standard conditions

Question 3

what is a salt bridge made from?

Answer 3

filter paper dipped in KNO3 solution

Question 4

what are the standard electrode conditions?

Answer 4

1.00moldm-3
100KPa
298K

Question 5

in what directions do electrons flow?

Answer 5

electrons flow from a more reactive metal to a less reactive one!

Question 6

what is the purpose of the salt bridge?

Answer 6

to complete the circuit by allowing ions to flow between the half cells (this balances the charge)

Question 7

what is the purpose of the standard hydrogen electrode?

Answer 7

it is used as a reference to measure standard electrode potentials

Question 8

ROOR

Answer 8

reduced form | oxidised form || oxidised form | reduced form

Question 9

what can electrochemical cells be used as?

Answer 9

a commercial source of electrical energy

Question 10

what are the 3 types of cells?

Answer 10

non-rechargeable cells
rechargeable cells
fuel cells

Question 11

what reaction occurs at the negative electrode in a lithium cell?

Answer 11

Li → Li+ + e–

Question 12

what reaction occurs at the positive electrode in a lithium cell?

Answer 12

Li+ + CoO2 + e- → Li+[CoO2]-

Question 13

what electrodes do lithium ion cells consists of? what is the electrolyte?

Answer 13

lithium cobalt oxide electrode & graphite electrode

electrolyte = lithium salt

Question 14

what is the most common fuel cell and what is the waste produce of this?

Answer 14

hydrogen fuel cell
only waste product = water

Question 15

pros of fuel cells

Answer 15

only waste product is water
more efficient
don’t need to recharge

Question 16

cons of fuel cells

Answer 16

hydrogen is flammable so must be stored and transported correctly - expensive process
energy needed to make H2 and O2 in the first place - process may use fossil fuels

Question 17

what are the electrode reactions in an alkaline hydrogen-oxygen fuel cell?

Answer 17

2H2 + 4OH- → 4H2O + 4e-

O2 + 2H2O + 4e- → 4OH-