Practical 8 FAQ Flashcards
Which is more reactive of copper and zinc?
Zinc so it is oxidised
Why is platinum a suitable electrode?
Unreactive and conducts electricity
What is the voltage of a standard hydrogen half cell?
Zero
Which side is standard hydrogen electrode located on?
Left hand side
Standard conditions of standard hydrogen electrode
H2 gas pumped at 100kPa pressure
Electrolytes contain H+ ions of 1moldm-3 conc
Platinum electrode
298K
Cell representation of standard hydrogen half cell
Pt(s) | H2(g) | H+(aq) ||
Why can an electrochemical cell not be recharged?
Reactions not reversible
Give an environmental advantage of using rechargeable cells.
Metals used
Give an environmental disadvantage of using rechargeable cells.
Mains electricity used to recharge, which may come from combusting fossil fuels, which releases CO2.
What could happen if standard conditions are changed?
Equillibria could shift right- more product, less reactants- Electrode potential more positive VICE VERSA
Alkali hydrogen fuel cell
Anode/oxidation:
H2 + 2OH- <–> 2H2O + 2e-
Cathode/reduction:
1/2O2 + H2O + 2e- <–> 2OH-
OVERALL: H2+ 1/2O2 <–> H2O
Acid hydrogen fuel cell
Anode/oxidation:
H2 <–> 2H+ + 2e-
Cathode/reduction:
1/2O2 + 2H+ 2e- <—> H2O
OVERALL: H2 + 1/2O2 <—> H2O
6 marker
Stage 1: Preparing solution
(1a) Weigh 8.00 g TiOSO4
(1b) Add (0.50 mol dm-3) sulfuric acid
(1c) Transfer to volumetric flask and make up to the 200cm3 mark
Stage 2: Set up cell
Content can be shown in a labelled diagram
(2a) piece of Ti immersed in (1 mol dm−3 acidified) TiO2+(aq) / the solution
(2b) (connect solutions with) salt bridge or description
(2c) (connect metals through high R) voltmeter
Stage 3: Measurements and calculation
(3a) record voltage/potential difference/emf of the cell
(3b) Ecell = ERHS – ELHS
Ecell = Ecopper – Etitanium
(3c) ELHS = ERHS – Ecell OR Ecell should be +1.22 V if Cu on RHS (or −1.22 if Cu electrode on LHS)
