The main objective of this experiment is to carry out qualitative analysis to identify metal cations in unknown solution 1.
An unknown material can be determined by using simple chemical tests and separations which is called as inorganic qualitative analysis. The separation of cations depends on the difference in their propensity to form precipitates. Separation scheme is used to classify cation into five groups on the basis of their physical and chemical behavior opposed to some reagents. Classification is based on whether there is formation of precipitates or not when metal cations react with the reagent. The five groups of cations and the characteristics of these groups are as follows:
i. Group I
Ag+, Hg+, …show more content…
The process to identify sample that only contain single cation is easier and straightforward. Whereas the detection of a particular ion in a sample that contains several ions is more difficult. This is due to the presence of the large number of ions that interfere with the test and the difficulty to distinguish between the cations that have similar chemical properties. To solve this problem, systematic separation that involve precipitating and removing of ions is used so that the mixture of cations will only have few ions. The separation of cations depends upon the difference in their tendencies to form precipitates, or to form complex ions.
In this experiment, an unknown solution 1 was given in order to identify the metal cations. The metal cations present were predicted by the color of precipitates as well as the solubility of precipitates in excess of the reagent. The procedure involved in this qualitative analysis only determined the possible group of metal cations.
Based on our observation white precipitate was formed when the unknown solution was added with HCl. This indicate that Ag+, Hg2+ and Pb2+ ion that belong to group I cations were present in the solution. These metal ions combine strongly with chloride ion to give insoluble chloride as the metal of qual scheme group I are soft acids. The ions of Group I insoluble chlorides:
M+ + Cl- MCl
Where M+ =