Presence of Fe(II) ions causes the formation of precipitates.
name: Qualitative reaction on Fe(II) ions with potassium hexacyanoferrate and potassium hydroxide is demonstrated.
Qualitative analysis is the determination of the presence of an element in the compounds and mixtures without estimation of its amount. Qualitative reactions are one of the most common tools of qualitative analysis. If the sample under study contains ions specific to the qualitative reaction the release of gas bubbles or precipitate formation or color change is expected. This experiment demonstrates the way to detect 2+ ions. Iron (II) sulfate is used for testing qualitative reactions on Fe2+ ions. When iron (II) sulfate solution is mixed with potassium hexacyanoferrate (III) solution it forms a dark blue precipitate of iron (II) hexacyanoferrate (III)
3Fe2+ + 2[Fe(CN)6]3- → Fe3[Fe(CN)6]2-
Potassium hydroxide could also be used for detecting Fe2+ ions. It reacts with Fe2+ ions producing a greenish-white iron (II) hydroxide.
Fe2+ + 2OH- → Fe(OH)2