Mole Concept

anpanman SG

A solution of FeSO4.(NH4)2.6H2O is 0.0500mol/dm3. What is the concentration in mol/dm3 with respect to (SO4)2-?

A 0.0250mol/dm3

B 0.0500mol/dm3

C 0.100mol/dm3

D 0.200 mol/dm3

And is graphite a carbon compound? (yes, i think. Suppose they are referring to C compound as compounds containing C atoms?)

Thanks!

ThunderFbolt SG

1 mole of (SO4)2- to 1 mole of FeSO4.(NH4)2.6H2O, so should be B.

And graphite is a carbon allotrope, not compound. Allotropes are elements that can have different structural modifications.

anpanman SG

Hi everyone!

My teacher said the answer to this question is C. However she told us to do the workings and try it out ourselves. don't really understand how to get the answer.

Thanks for helping ThunderFbolt

UltimaOnline SG

A solution of FeSO4.(NH4)2.6H2O is 0.0500mol/dm3. What is the concentration in mol/dm3 with respect to (SO4)2-?

A 0.0250mol/dm3

B 0.0500mol/dm3

C 0.100mol/dm3

D 0.200 mol/dm3

Thanks!

The question (at least as you typed it, or as your teacher gave it to you) is erroneous.

If the NH4+ ions are intended to be ligands, notice that there are no lone pairs on the N atom available for co-ordinate dative covalent bonding.

If the NH4+ ions are intended to be counter(balancing) ions, the question failed to specify the anion in the formula of the coordination compound (ie. the complex ions and its counter ions).

If the question is paraphrased to have the formula of the coordination compound given as (NH4+)2.[Fe(H2O)6]2+.(SO4 2-)n, then the molarity of sulfate(VI) ions would indeed be twice the molarity of the coordination compound.

There's your answer, anpanman.

ThunderFbolt SG

oh yea, didn't notice no lone pair =P