Editing Qualitative inorganic analysis (section)

==Sodium carbonate test==
{{Unreferenced section|date=May 2022}}
The sodium carbonate test (not to be confused with sodium carbonate extract test) is used to distinguish between some common metal ions, which are precipitated as their respective carbonates. The test can distinguish between copper (Cu), iron (Fe), and calcium (Ca), zinc (Zn) or lead (Pb). Sodium carbonate solution is added to the salt of the metal. A blue precipitate indicates Cu<sup>2+</sup> ion. A dirty green precipitate indicates Fe<sup>2+</sup> ion. A yellow-brown precipitate indicates Fe<sup>3+</sup> ion. A white precipitate indicates Ca<sup>2+</sup>, Zn<sup>2+</sup>, or Pb<sup>2+</sup> ion. The compounds formed are, respectively, [[basic copper carbonate]], [[iron(II) carbonate]], [[iron(III) oxide]], [[calcium carbonate]], [[zinc carbonate]], and [[lead(II) carbonate]]. This test is used to precipitate the ion present as almost all carbonates are insoluble. While this test is useful for telling these cations apart, it fails if other ions are present, because most metal carbonates are insoluble and will precipitate. In addition, calcium, zinc, and lead ions all produce white precipitates with carbonate, making it difficult to distinguish between them. Instead of sodium carbonate, [[sodium hydroxide]] may be added, this gives nearly the same colours, except that lead and zinc hydroxides are soluble in excess alkali, and can hence be distinguished from calcium. See qualitative inorganic analysis for the complete sequence of tests used for qualitative cation analysis.