Assuming standard conditions, answer the following questions. (Use the table of
ID: 952582 • Letter: A
Question
Assuming standard conditions, answer the following questions. (Use the table of Standard Reduction Potentials for common Half-reactions from your text. If hydrogen is one of the reagents, assume acidic solution.)
1) Is Cr3+(aq) capable of oxidizing Fe2+(aq) to Fe3+(aq)?
2) Is Cr metal capable of reducing Fe2+(aq)?
3) Is Sn metal capable of reducing Fe3+(aq) to Fe2+(aq)?
4)Is H2(g) capable of reducing Ni2+(aq)?
5) Is Fe2+(aq) capable of reducing Cr3+(aq) to Cr metal?
6)Is VO2+(aq) capable of oxidizing Fe2+(aq)?
Explanation / Answer
1) Is Cr3+(aq) capable of oxidizing Fe2+(aq) to Fe3+(aq)?
Fe3+ + e <-> Fe2+ 0.77
Cr3+ + e<-> Cr2+ 0.42
The reaction:
Fe3+ + e <-> Fe2+ E = 0.77
Cr2+ <->Cr3+ + e- E = 0.42
From, here, Cr+3 will OXIDIZE and Fe will reduce: therefore the answer is NO
2) Is Cr metal capable of reducing Fe2+(aq)?
Cr3+ + 3 e <--> Cr(s) 0.74
Fe2+ + 2 e <-> Fe(s) 0.44
the reaction that occurs spontanously:
Cr(s) <-> Cr3+ + 3 e E = 0.74
Fe2+ + 2 e <-> Fe(s) E = 0.44
then, Chromium will reduce Fe+2; answer is YES
3) Is Sn metal capable of reducing Fe3+(aq) to Fe2+(aq)?
Fe3+ + e <-> Fe2+ E = 0.77
Sn2+ + 2 e <-> Sn(s) 0.13
this will occurs spontaneously:
Fe3+ + e <-> Fe2+ E = 0.77
Sn(s) <-> Sn2+ + 2 e E = 0.13
Sn is being oxidized and reduces Fe, therefore the statement is TRUE
4)Is H2(g) capable of reducing Ni2+(aq)?
Ni2+ + 2 e <-> Ni(s) 0.25
2 H+ + 2 e <-> H2(g) 0.0000
then this occurs spontaneously
Ni(s) <-> Ni2+ + 2 e E = 0.25
2 H+ + 2 e <-> H2(g) 0.0000
that is, Nickel is reducing, therefore the answer is NO
5) Is Fe2+(aq) capable of reducing Cr3+(aq) to Cr metal?
Cr3+ + 3 e <--> Cr(s) 0.74
Fe2+ + 2 e <-> Fe(s) 0.44
the reaction that occurs spontanously:
Cr(s) <-> Cr3+ + 3 e E = 0.74
Fe2+ + 2 e <-> Fe(s) E = 0.44
answer is NO, Fe+2 will oxidize Chromium
6)Is VO2+(aq) capable of oxidizing Fe2+(aq)?
VO2+ + 2 H+ + e<-> V3+ + H2O +0.34
Fe2+ + 2 e <-> Fe(s) E = 0.44
this will occur spontaneously
VO2+ + 2 H+ + e<-> V3+ + H2O +0.34
Fe(s) <->Fe2+ + 2 e E = +0.44
then, the answer is YES; VO+2 will oxidize Fe