Question

You are given an unknown solution that only contains one of the two listed cations. Describe a simple test to distinguish between aqueous solutions of the following cations. State the distinguishing outcomes of the test and the indication of which cation is present. a: Al^3+ and Fe^3+ b: Fe(OH)3(s) and Ni(OH)2(s) c: Cr^3+ and CrO4^2- d: Ni^2+ and Fe^3+

Answer 1

Al^3+ and Fe^3+. Most iron(III) solution are lightly colored while Al&3+ solutions are not; however, if you want a more definitive test, add OH^-. Iron(III) hydroxide is red/brown while aluminum hydroxide is white.

Fe(OH)3 and NI(OH)2 --not the same color.

Cr^3+ and CrO4^2- --not the same color.

Ni^2+ and Fe^3+. -different color.