Chemistry question on Metals

anpanman SG

My teacher said that when iron rusts, a green substance is sometimes formed on the object... says it is Iron(III) or iron(II) oxide or ion? I can't remember. So here are the possible options:

a. iron(II) oxide

b. iron(III) oxide

c. iron(II) ion

d. iron(III) ion

Didn't really catch what my teacher said earlier, so it would be great if someone could provide me the exact answer. By the way, my textbook says the iron(III) oxide formed is reddish-brown in colour. But I'm sure I heard my teacher say green...

Many many thanks.

UltimaOnline SG

My teacher said that when iron rusts, a green substance is sometimes formed on the object... says it is Iron(III) or iron(II) oxide or ion? I can't remember. So here are the possible options:

a. iron(II) oxide

b. iron(III) oxide

c. iron(II) ion

d. iron(III) ion

Many many thanks.

Fe2+ in solid state, eg. Fe(OH)2 (s) is dirty green.
Fe2+ in aqueous state, eg. Fe(Cl)2 (aq) is pale green.
Fe3+ in solid state, eg. Fe(OH)3 (s) is reddish brown.
Fe3+ in aqueous state, eg. Fe(Cl)3 (aq) is yellow.

ZarpZ SG

Iron (III) Oxide is definitely not Green.
Iron (III) Oxide is reddish brown like according to UltimaOnline.

The answer is either, a or c.
But i'm going with (a).
Due to the fact of oxygen reacting on it.

Can anybody reconfirm this?

tinuviel07 SG

iron (ii) oxide ftw

Garrick_3658 SG

It's (a).

This is a good question, testing on your understanding of QA (or memorising) and particulate model of matter.

Remember, REAL MATTER MAY BE COLOURED, BUT PARTICLES OF MATTER ARE NEVER COLOURED. (edit: ok maybe i got confused, but does this apply here? I think it goes under the particles in a solid, liquid, gas etc)

anpanman SG

It's (a).

This is a good question, testing on your understanding of QA (or memorising) and particulate model of matter.

So is it true that a GREEN substance is formed on an object that rusts sometimes?

Garrick_3658 SG

Iron(II) or iron(II)-containing compounds, yes.

davidche SG

So is it true that a GREEN substance is formed on an object that rusts sometimes?

I think what happens is that it first changes to iron(II) oxide. After a longer time of rusting, it gets oxidised to Iron(III) oxide which is reddish brown in colour, like the rust we usually see.