IA on investigating the purity of aluminium sources (foil, powder, metal) using sodium hydroxide.

1. net eqn
H2 fuel cell- acidic electrolyte
(-ve) (Anode) - Oxidation
2H2 → 4H+ + 4e−
+ ve (Cathode)- Reduction
4H+ + O2 + 4e− → 4H2O
2H2 + O2 → 2H2O O2
H2
PEM – made of Teflon
allow H+ ion to flow
Proton Exchange Membrane
H2O
Catalyst – platinum used anode/cathode
To determine the purity of Aluminium (foil, metal, powder) using NaOH
Hydrogen is used for fuel cell.
Aluminium is reactive – but will not react with acid as it forms a stable aluminium oxde layer.
NaOH is used to corrode away oxide layer, expose reactive AI metal.
NaOH acts as a catalyst. Source of H2 using aluminium.
Purity of any aluminium source can be determined.
Aluminium powder, strip, and foil will be tested
Al + 6H2O + 2NaOH → 2Na[AI(OH)4] + 3H2
2AI + 6H2O → 2AI(OH)3 + 3H2
Reaction mechanism
Procedure:
4ml 6M NaOH added to 0.01g
AI foil, powder and metal
0.01g AI will produce – 12.61 cm3
Gas will be collected over water.
Purity of AI foil can be determined
AI foil
2 mole AI – 3 mol H2 gas
54 g AI – 3 mol H2 gas
0.01g – 0.00055 mol gas
(1mol gas – 22700 cm3)
0.00055 mol – 12.61cm3
H2 gas

2. Collection of gas temp at 23C Rxn happen at 6M NaOH
Purity of AI from powder, metal and foil
Source Mass AI
used/g
Expt
yield
Theoretical
yield
Purity
Aluminium
powder
0.01 12.5 12.6 99.2%
Aluminium
metal
0.01 12.0 12.6 95.0%
Aluminium
foil
0.01 12.5 12.6 99.2%
Data collected.
Aluminium foil and powder has very good purity.
Metal might be contain impurities.
To determine the purity of Aluminium (foil, metal, powder) using NaOH
2 mole AI – 3 mol H2 gas
54 g AI – 3 mol H2 gas
0.01g – 0.00055 mol gas
(1mol gas – 22700 cm3)
0.00055 mol – 12.61cm3
H2 gas
92
93
94
95
96
97
98
99
100
Aluminium powder Aluminium metal Aluminium foil
%
purity
Al source vs % purity

3. Collection of gas temp at 23C Rxn happen at 6M NaOH
Purity of AI from powder, metal and foil
To determine the purity of Aluminium (foil, metal, powder) using NaOH
1. What is the activation energy for rxn bet AI + NaOH
2. Which catalyst is better, NaOH or KOH?
3. Will reaction with KOH produce the same rate as NaOH
4. What is the order for the rxn bet AI + KOH, will it be 1st order
5. Is it possible for AI to react with HCI instead of NaOH
6. AI will only react with HCI at a certain temp, which is above 60C.
7. What is the activation energy for AI with acid, HCI.
8. Will it be lower or higher than AI with NaOH.
9. To find the purity of AI from various sources, like AI foil, Al metal and AI powder.
Possible research questions