# Homework Help: Coord. compound

1. Aug 6, 2009

### XTEND

1. The problem statement, all variables and given/known data
A coord. compound of mercury (II) is found to contain the sulfate ion and the potassium ion as well as Hg+2. Ba(NO3)2 solution is added to a water solution of this compound, but there is no precipitate. If the coord. # is 4, and a H20 solution of the compound shows an electrical conductivity equal to 7 ions per formula unit, what is the formula?

2. Relevant equations

N/A

3. The attempt at a solution

[Hg(SO4)4]K2

not sure ???

2. Aug 8, 2009

### kldickson

The sulfate ion isn't a ligand.

3. Aug 9, 2009

### Fightfish

Are you sure its a sulfate and not a sulfite ion? Cos' like kldickson mentioned, the sulfate ion isn't a ligand, yet there are no free sulfate ions since no ppt is formed with barium nitrate. Also, the species that you mentioned there is not a compound - it has a net negative charge.

4. Aug 9, 2009

### XTEND

ya it must be SO3

But what about the name of the compound? I must be way off???

5. Aug 10, 2009

### Fightfish

Then its probably K6 [Ag(SO3)4], though i have doubts about the feasibility of its formation. Not sure about the nomenclature of sulfite ligands and the "anionic complex-ed" mercury

6. Aug 10, 2009

### kldickson

Set up a reaction between the barium nitrate and the mercury-potassium-sulfate solution.

Also, if I am correct, anions typically aren't ligands.

7. Aug 11, 2009

### Fightfish

Not true, anions are in fact rather common ligands since they are stronger ligands than water. For instance, some common ligands are Cl- and CN-.

8. Aug 11, 2009

### kldickson

Fightfish, you're right about the anions.

9. Aug 11, 2009

### Staff: Mentor

Not particullarly efficient at complexing, nonetheless some of its complexes have overall stability constants in the 104 range.

Mercury SO32- complexes are much much more stable.

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