In: Chemistry
Answer the following questions using the results of the following Unknown Solution Analysis:
Flame test: red flame Solutions reactions:
ammonium carbonate - white precipitate (ppt.) ammonium phosphate - white ppt. ammonium sulfate - white ppt. Halide test: purple hexane layer
a) What is the complete chemical name of the unknown ionic compound?
b) What is its correct chemical formula?
Two metal ions give a red flame in the flames test. These are calcium (Ca, gives a transient brick red flame) and strontium (Sr, gives a persistent red flame). Both Ca and Sr reacts with ammonium carbonate to give insoluble carbonates. Ca and Sr forms insoluble phosphates with ammonium phosphate. However, calcium sulfate (CaSO4) is soluble in water while strontium sulfate (SrSO4) is insoluble. Since the metal ion formed three precipitates, hence, we cannot have Ca, Therefore, we have Sr as the metal.
The hexane layer of the halide gives a purple color and this is characteristic of iodide (I-).
a) The chemical name of the unknown ionic compound is strontium iodide.
b) The chemical formula of strontium iodide is SrI2.