1) production of lead from the ore galena,pbs, involoves several steps. In the f
ID: 807422 • Letter: 1
Question
1) production of lead from the ore galena,pbs, involoves several steps. In the first step's overall reaction, Pbs is oxidized to PbO and SO2 by (O2)i.e.,
2PbS + 3O2 --> 2PbO + 2SO2
a)Which element is oxidized?
b)Which element is reduced?
Must show all the steps used
Oxidation:
Reduction:
(d) Use these two half reactions to generate a balanced equation for the oxidation of Pbs:
2) Evaluate each of the pairs shown in the table for solubility over the entire composition range. Place an X under the expected solubility for each of the pairs. Indicate which of the Hume-Rothery rules are not met in each case where complete solubility is not supported.
pair
Complete
solubility
Limited solubility
No Solubility
H-R Rules Not Met
Cr-Fe
Ti-Fe
Fe-Cu
Ni-Cu
Cu-Co
Ag-Pt
Construct a table using the data
element Radius crystal structure EN
the data
element Radius Crystal structure Electronegativity
Ni 115 FCC 1.8
C 77
H 32
O 73
Ti 132 HCP 1.54
Ag 134 FCC 1.93
Al 118 FCC 1.61
Cu 117 FCC 1.90
Co 116 HCP 1.88
Cr 118 BCC 1.66
Fe 117 BCC 1.83
Pt 130 FCC 2.28
Au 134 FCC 2.40
Zn 125 HCP 1.65
Ir 127 FCC 2.2
3) a) A face centered cubic lattice contains an interstitial space in the body center. For a host element of 200pm radius, calculate the radius of the octahedral interstitial space.
b) which elements fit in this space?
pair
Complete
solubility
Limited solubility
No Solubility
H-R Rules Not Met
Cr-Fe
Ti-Fe
Fe-Cu
Ni-Cu
Cu-Co
Ag-Pt
Explanation / Answer
1a) Sulfur is oxidised
1b) Oxygen
1c) Oxidation: Pb2+ + S2- ------> Pb2+ + S4+ +6e-
Reduction: Pb2+ + O2 + 4e- -------> Pb2+ + 2O2-
1d) Adding 2*oxidation reaction to 3*reduction reaction (excluding the lead ions) balances the no. of electrons on both the sides, hence yields the balanced equation
2Pb2+ + 2S2- +3O2 ------> 2Pb2+ + 2S4+ + 6O2-
Or 4PbS + 3/2 O2 ------> 2PbO + 2SO2
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