Question

Use solubility rules and other properties to separate the given ions (Ba²⁺, Ag⁺, and Fe³⁺)

Ba²⁺, Ag⁺, and Fe³⁺ mixed in one beaker. Real compounds dissolved: Ba(NO₃)₂, AgNO₃ and Fe(NO₃)₃; 0.1 mol/L for all.

You may need to precipitate them one by one.

HNO₃, NaI, Na₂SO₄, NaOH, NaHCO₃, Na₂CO₃, Na₃PO₄, filter paper, funnel, and Erlenmeyer flasks are available to accomplish the task.

Three solid samples total should be obtained.

What is a procedure for separating the given ions?

Answer 1

You have three ions in solution (Ba2+, Ag+ and Fe3+)

First

You need to select for each ion a counterion to react with, and predict the reaction,for example:

Ba^₂₊

For each of the products of the reaction you need to look for the solubility product constant Ksp, any chemistry book has all those values, if the number is not in the list, it means that the compund is highly soluble and that reaction is useless. In the example I just wrote there are no value for the Ksp for BaI2, it means that you need to move to the next trial.

In this case for the three ions, I can suggest:

Ksp=8.5x10^-17

Ksp=1.1x10^-10

Ksp=4x10^-38

As you can see all the values are very low, it means that the compounds are going to precipitate.

Now the procedure, I suggest you to perform the reactions in the order I wrote them, that is because part of the Ag also can precipitate as Sulfate and can mix with the barium.

So first you add 0.1 mol/L of NaI and stir thoroughly, then you filter the precipitate that is formed, this is the Ag

Second add 0.1mol/L of Na2SO4 and stir thoroughly then filter the precipitate formed, this is the Ba

Third add 3 times the volume added before of 0.1mol/L of NaOH and stir thoroughly then filter the precipitate formed, this is the Fe, it ir important this step should be done at the last, because this will rise the pH