Chemistry question on Metals

• anpanman

  14 Oct 08, 20:07

  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

  14 Oct 08, 21:39

  Originally posted by anpanman:

  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.

   

   

  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

  14 Oct 08, 21:59

  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...

   

  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

  15 Oct 08, 01:01

  iron (ii) oxide ftw

• Garrick_3658

  15 Oct 08, 01:11

  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

  15 Oct 08, 15:42

  Originally posted by Garrick_3658:

  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)

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

• Garrick_3658

  15 Oct 08, 19:04

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

• davidche

  15 Oct 08, 19:11

  Originally posted by anpanman:

  
  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.