To determine the cation in each of the unknown substance X, Y and Z by observing the flame colour of different metal compounds.
A distinctive feature of many s-block metals is their ability to produce flame colours.
At temperature of a Bunsen flame, a compound will decompose to give gaseous atoms of its constituent elements. When an electron in the gaseous atom absorbs energy from the flame, it will move from an orbital with lower energy to an orbital with higher energy. When such an electron returns from an orbital of higher energy to an orbital of lower energy, a photon with energy equal to the difference in energy of the two orbitals will be emitted. An emission line …show more content…
Besides, the sample of powdered compound whose flame colour is to determined is easier to stuck on the platinum wire. 3. Substance A gives a golden yellow flame in flame test.
When an acidified solution of A is treated with silver nitrate solution, a yellow precipitate is formed. The precipitate is insoluble in excess ammonia solution. Name A.
Substance A is sodium iodide.
The range of detected elements is small, and the test relies on the subjective experience of the experimenter rather than any objective measurements. The test has difficulty detecting small concentrations of some elements, while too strong a result may be produced for certain others, which tends to drown out weaker signals.
Moreover, the test cannot differentiate between all elements. Several metals produce the same flame color while some compounds do not change the color of the flame at all.
Source of error
The source of error of the experiment include the subjective judgment of the colour by the human eye.
Besides, the traces of Impurities from the last substance tested and the position of the wire put in the flame also affect the accuracy of the experiment.
The wire should be moved first through the cooler