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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: ssssss on October 14, 2004, 08:49:48 AM

Title: Moles,Equivalents Etc
Post by: ssssss on October 14, 2004, 08:49:48 AM
So i am on the verge of finishing and throughly revising My Stoichiometry Syllabus.These are the problems i want to clear:

1.I once asked how to calculate the Equivalent weight of Co-ordination Compounds?But i am Confused again with it.Please tell me the proper manner to find it.Please solve these compound as an Example K4Fe[CN]6.
2.Is [NH]4PbCl6 a Co-ordinate compound?What is its Equivalent weight.
3.Equivalent weigh of Mo4O3[C2O4]212H2O
4.Please tell are these reactions possible:

Na2SO4 + HCL-------->???

KClO3 + HCL---------->???

CaSO4 + NaOH--------->???


Title: Re:Moles,Equivalents Etc
Post by: Demotivator on October 14, 2004, 07:13:22 PM
As you know, the equiv wt is the amount to react completely with one equiv of something else.  But first, you have to determine what that something is.

With coordination compounds, its assumed that we're talking about the capacity for ligand transfer. (Coord compounds can also do electron transfer in which case the equiv wt would be different).

for K4Fe[CN]6 , there are six cordination sites for the six ligands (CN).
So eq wt = MW/6  .  That's the amount to react  completely with one equiv of a donor.

NH]4PbCl6  is again 6 sites.  MW/6

Mo4O3(C2O4)212H2O
This one is tricky. C2O4 is a bidentate ligand. 2 of them makes a total of four sites. But is O cosidered a ligand or a fixed oxide?  I'm not 100% sure but I don't think it  is a coordination ligand.  Is H2O (12 of them) a ligand?  I think its water of crystallization by the way it's written, not ligand.
So, eq wt = MW/4
Title: Re:Moles,Equivalents Etc
Post by: AWK on October 15, 2004, 01:59:59 AM
Coordinates compouds are salts. So equivalent is calculated in the same manner as for salts.
K4Fe[CN]6 - eq=1/4 mole
(NH4)2[PbCl6] - eq=1/2 mole
But in specific reaction, eg
K4Fe[CN]6 + 6HCl = 4KCl + FeCl2 +6HCN - eq=1/6 mole
(NH4)2[PbCl6] +6AgNO3 = 6AgCl + Pb(NO3)2 + 2NH4NO3 - eq=1/6 mole

I cannot guess, what structure of Mo4O3(C2O4)2.12H2O can be
Title: Re:Moles,Equivalents Etc
Post by: ssssss on October 15, 2004, 02:22:51 AM
Quote from: Demotivator on October 14, 2004, 07:13:22 PM
As you know, the equiv wt is the amount to react completely with one equiv of something else.  But first, you have to determine what that something is.

With coordination compounds, its assumed that we're talking about the capacity for ligand transfer. (Coord compounds can also do electron transfer in which case the equiv wt would be different).

for K4Fe[CN]6 , there are six cordination sites for the six ligands (CN).
So eq wt = MW/6  .  That's the amount to react  completely with one equiv of a donor.

NH]4PbCl6  is again 6 sites.  MW/6

Mo4O3(C2O4)212H2O
This one is tricky. C2O4 is a bidentate ligand. 2 of them makes a total of four sites. But is O cosidered a ligand or a fixed oxide?  I'm not 100% sure but I don't think it  is a coordination ligand.  Is H2O (12 of them) a ligand?  I think its water of crystallization by the way it's written, not ligand.
So, eq wt = MW/4



Oh yes is water of Crystalization.
Title: Re:Moles,Equivalents Etc
Post by: ssssss on October 15, 2004, 07:53:30 AM
Ok this is what My course material say about Equivalent weights.Tell is this correct to follow..

Equivalent weight of elements=Mol wt/valency

Equivalent weight of compound=Mol wt/Total charge on cationic or anionic part

Equivalent weight of salt is similar to that of compound,no need to consider the water of crystalization.

Equivalent weight of ions=Mol Wt/charge on ion


Yet to Do the redox reaction Topic.Eq Wt. in Redox reactions is somewhat more Complex than Simple reactions.

Thanks