Suppose you were given three unlabelled solutions. You know that one contains Iron (II) ions, another contains Iron (III) ions and the third has Silver ions, but you don’t know which is which. Devise a scheme by which you could identify each of the three cation solutions.
Color: Fe+2 solutions are pale green. Fe+3 are brown to yellowish brown, unless in acidic solutions. Silver solutions are colorless.
consider looking at color:
clear>Fe+3 in acid, or silver
so dip pH paper in, if it is not acid, it is silver. If it is clear, and acidic, Fe+3
pale green> Fe+2
brown, or brown/yellow> Fe+3
If I answer this for you then I'm doing your thinking but this question is designed to make you think. Think about reactions that iron(II), iron(III) and Ag(I) undergo which give different results. Think about the color of some of the ppts. As an example, consider adding dilute HCl (or a solution of NaCl) to the three. What will happen that might identify one or more of the ions?
To identify each of the three cation solutions (one containing Iron (II) ions, one containing Iron (III) ions, and one containing Silver ions) without labels, you can use a combination of chemical reactions and observations. Here's a scheme to follow:
1. Start by taking small portions of each solution in separate test tubes.
2. To identify the Iron (II) ion solution, add a few drops of potassium thiocyanate (KSCN) solution to one of the test tubes. If a reddish-brown color appears, it indicates the presence of Iron (II) ions, as Iron (II) forms a deep red compound with thiocyanate ions.
3. To identify the Iron (III) ion solution, add a few drops of potassium ferricyanide (K3Fe(CN)6) solution to another test tube. If a bluish-green precipitate forms, it indicates the presence of Iron (III) ions. Iron (III) reacts with ferricyanide ions to form a distinct precipitate known as Prussian Blue.
4. To identify the Silver ion solution, add a few drops of hydrochloric acid (HCl) to the remaining test tube. If a white precipitate forms, it indicates the presence of Silver ions. Silver reacts with chloride ions to form a white precipitate of silver chloride.
By observing the reactions in each test tube, you can identify which solution contains Iron (II) ions, which contains Iron (III) ions, and which contains Silver ions. Remember to perform these tests carefully in a well-ventilated area and follow appropriate safety guidelines.