Preparation of solution for cation testing on the semimicro scale

8 PREPARATION OF SOLUTION FOR CATION TESTING ON THE SEMIMICRO SCALE 

If the substance dissolves in water, proceed immediately to the test for the metal ions. If the use of dilute hydrochloric acid results in the formation of a precipitate, this may consist of the metals of Group I the precipitate may either be filtered off and examined for Group I or else the original substance may be dissolved in dilute nitric acid. If concentrated acids are employed for dissolution, the remarks in the first paragraph must be borne in mind. 

Oxides, hydroxides, free metals, and simple alloys If a solid substance is found to contain no anions, it may be an oxide, or hydroxide, or a metal or a mixture of metals, or an alloy. Metals and alloys have certain characteristic physical properties many metals evolve hydrogen on treatment with dilute acids. As a rule, nitric acid must be employed as solvent, and it will then be necessary to remove the excess nitric acid (as already described above) before proceeding to the Group analysis. 

When a suitable solvent has been found, prepare the solution for analysis using about 50 mg of the solid the volume of the final solution should be 1-1-5 ml. Use this solution for the separation of cations into groups according to Section VI.9. 

---