[Rutherford]

Can HCl oxidize iron to Fe³⁺?
Can it oxidize Fe²⁺ to Fe³⁺?
When looking at the red-ox potentials, first is possible, the second isn't. Is this true?

[Sophia7X]

 Fe+2 doesn't oxidize to Fe+3 in HCl. I've made a solution of Fe+2 in 2 M HCl before and it did not change color.

[Rutherford]

Okay, the red-ox potentials say the same. Thanks.
Now, is the first reaction possible? By red-ox it should be, but I am not sure (the oxidation potential is only slightly bigger than that of H⁺).

[Sophia7X]

When you put steel wool in HCl, the solution will turn pale green which indicates Fe(II) but if you leave it out (uncovered) for a couple hours, the Fe(II) readily converts to Fe(III) (turns yellow-brown) because of the air.

I don't think you'll get Fe(III) directly from Fe instantly. Interestingly, you can reverse it by adding more steel wool to get back Fe(II).

Also, I believe iron rust in HCl will form Fe3+.

[Rutherford]

I am confused now.

Fe+2 doesn't oxidize to Fe+3 in HCl. I've made a solution of Fe+2 in 2 M HCl before and it did not change color.

When you put steel wool in HCl, the solution will turn pale green which indicates Fe(II) but if you leave it out (uncovered) for a couple hours, the Fe(II) readily converts to Fe(III) (turns yellow-brown) because of the air.

I don't think you'll get Fe(III) directly from Fe instantly. Interestingly, you can reverse it by adding more steel wool to get back Fe(II).

Also, I believe iron rust in HCl will form Fe3+.

For Fe²⁺ to Fe³⁺ you said no, but then yes.
According to red-ox potentials, it is easier to oxidize iron to +3, than from +2 to +3 which is not very logical. Why is this so?

[Borek]

For Fe²⁺ to Fe³⁺ you said no, but then yes.

Leaving uncovered means something else than just preparing a solution.

[Rutherford]

I think I understood. It is because these reactions are reversible and have equilibrium constant, so after some time equilibrium is established and there will be some amount of Fe³⁺ although Fe²⁺ if favored. Sophia no offense, I just misunderstood this. Thanks Borek for the correction. But I am still curios about this:
According to red-ox potentials, it is easier to oxidize iron to +3, than from +2 to +3 which is not very logical. Why is this so?

[Borek]

I am not convinced you understand the situation. When the solution is left UNCOVERED another reaction takes place.

[Hunter2]

Iron get oxidized from Fe²⁺ to Fe³⁺ by oxygen. The air has access to the solution, that is meant by " uncovered".

[Rutherford]

Oh, okay.