Which of the following reagents would oxidize Cr to Cr2 , but not Fe to Fe3 ?

Ca Co Ca2+ Br2 Co2+ Br-

Which of the following reagents would oxidize Cu to Cu2 , but not Cl– to Cl2?

Br2 Ca Co2+ Co Br- Ca2+

To determine which reagents would oxidize Cr to Cr2 but not Fe to Fe3:

We need to compare the reduction potentials of the species involved. Reduction potentials indicate the tendency of a species to be reduced (gain electrons) or oxidized (lose electrons). The higher the reduction potential, the stronger the oxidizing agent.

Looking at the given reagents, we need to compare the reduction potentials of Ca, Co, Ca2+, Br2, Co2+, and Br-.

From the given options, Br2 and Br- have the highest reduction potentials, indicating that they have a stronger tendency to be reduced (act as an oxidizing agent).

Therefore, Br2 is the reagent that would oxidize Cr to Cr2 but not Fe to Fe3.

To determine which reagents would oxidize Cu to Cu2 but not Cl- to Cl2:

Again, we need to compare the reduction potentials of the species involved. This time, we are comparing Cu, Cl-, Br2, Ca, Co2+, and Ca2+.

From the given options, Br2 and Cl- have the highest reduction potentials. This suggests that Br2 is the strongest oxidizing agent and Cl- can be reduced to Cl2, making it a weaker oxidizing agent compared to Br2.

Therefore, Br2 is the reagent that would oxidize Cu to Cu2 but not Cl- to Cl2.

To determine which reagents can oxidize Cr to Cr2+ but not Fe to Fe3+, or oxidize Cu to Cu2+ but not Cl– to Cl2, we need to look at the redox potentials of each reaction.

The reagent that can cause oxidation will have a higher redox potential than the element it is oxidizing. On the other hand, if the redox potential of the reagent is lower than the redox potential of the element, it will not cause oxidation.

Let's check the redox potentials for each reaction:

For the oxidation of Cr to Cr2+: Cr -> Cr2+
We need a reagent that has a higher redox potential than Cr. By comparing the standard reduction potentials, we find that Br2 (bromine) has a higher redox potential than Cr. Therefore, Br2 can oxidize Cr to Cr2+.

For the oxidation of Fe to Fe3+: Fe -> Fe3+
We need a reagent that has a higher redox potential than Fe. By comparing the standard reduction potentials, we find that Br2 (bromine) has a higher redox potential than Fe. Therefore, Br2 can also oxidize Fe to Fe3+.

As for the oxidation of Cu to Cu2+: Cu -> Cu2+
We need a reagent that has a higher redox potential than Cu. By comparing the standard reduction potentials, we find that Br2 (bromine) and Co2+ (cobalt) have higher redox potentials than Cu. Therefore, both Br2 and Co2+ can oxidize Cu to Cu2+.

For the oxidation of Cl– to Cl2: 2Cl– -> Cl2
We need a reagent that has a higher redox potential than Cl–. By comparing the standard reduction potentials, we find that none of the listed reagents have a higher redox potential than Cl–. Therefore, none of the given reagents can oxidize Cl– to Cl2.

In summary:
- Br2 can oxidize both Cr to Cr2+ and Fe to Fe3+.
- Co2+ can oxidize Cu to Cu2+.
- None of the given reagents can oxidize Cl– to Cl2.

For #1, find Cr^2+ +2e ==> Cr in the tables. You want the reverse of this or Cr ==> Cr^2+ + 2e E = +0.91 so anything below it in your table will work. Find Fe ==> Fe^3+ + 3e and you want the reverse of that or

Fe ==> Fe^3+ + 3e = ? I couldn't find that in my table. Thenlocate those elements/ions above. Any thing above Fe will not oxidize it and anything below Cr will oxidize it so those between the two will satisfy the question. Since I couldn't locate Fe I can't put any other numbers on this. One caution, Since Cr ==> Cr^2+ + 2e is an oxidation the other reaction MUST BE A REDUCTION; I.E.,
metal ion + e ==> metal or
non-metal + e ==> non-metal ion which eliminates Co (but perhaps not Co^2+) and Ca(perhaps not Ca^2+) and Br^- (but perhaps not Br2)

adfa