What can be added to a solution containing I-(aq) ions to precipitate the ions from the solution?

Question

1. Sodium chloride 

 

2. Magnesium nitrate 

 

3. Lead (II) nitrate 

 

4. Two of the above 

 

5. All of the above 

 

Im not sure but I think it’s two of the above! 

Answer 1

Hello Karen

 

As Lauren has stated, lead (II) iodide is insoluble in water, therefore, lead (II) nitrate is the only answer.  Lead (II) nitrate is soluble in water, but when combined with a solution containing I^-, it will form insoluble PbI₂ as a precipitate.

 

The net ionic equation is written as:

 

Pb²⁺ (aq) + 2I- (aq) → PbI₂ (s)

 

You can't use sodium chloride or magnesium nitrate because both NaI and MgI₂ are water soluble.

Answer 2

Lead II nitrate is insoluble.

 

You need mercury, silver or lead to make an insoluble iodide.