To test for Fe²⁺, a little sodium hydroxide solution is added to the aqueous solution and then in excess. If Fe²⁺ ions are present:
A dirty green gelatinous precipitate of iron (II) hydroxide is formed, which is soluble in excess sodium hydroxide.
A reddish-brown gelatinous precipitate of iron (III) hydroxide is formed, which is insoluble in excess sodium hydroxide.
A dirty green gelatinous precipitate of iron (II) hydroxide is formed, which is insoluble in excess sodium hydroxide.
A reddish-brown gelatinous precipitate of iron (III) hydroxide is formed, which is soluble in excess sodium hydroxide.
