1458 WordsFeb 16, 20146 Pages
PROJECT IN CHEM LAB. Submitted by: BHEA MARIE MENDOZA Submitted to: -CATIONS and ANIONS- Cations are positive charged ions. A cation has fewer electrons than protons. Anions are negatively charged ions. An anion has more electron than protons. The nature and magnitude of charge on ion depend on the position of an element in the periodic table. In forming an ion, an atom of a main group element loses gains electrons to obtain the electronic configuration of the noble gas closest to it in the periodic table. This gives the ion on especially stable electronic arrangement with a completely filled shell of electrons; that is, the electrons completely fill the shell farthest from the nucleus. For example, sodium…show more content…
In an educational setting, it is generally true that the concentrations of the ions to be identified are all approximately 0.01 M in an aqueous solution. The 'semimicro' level of qualitative analysis employs methods used to detect 1-2 mg of an ion in 5 mL of solution. First, ions are removed in groups from the initial aqueous solution. After each group has been separated, then testing is conducted for the individual ions in each group. Here is a common grouping of cations: Group I: Ag+, Hg22+, Pb2+ Precipitated in 1 M HCl Group II: Bi3+, Cd2+, Cu2+, Hg2+, (Pb2+), Sb3+ and Sb5+, Sn2+ and Sn4+ Precipitated in 0.1 M H2S solution at pH 0.5 Group III: Al3+, (Cd2+), Co2+, Cr3+, Fe2+ and Fe3+, Mn2+, Ni2+, Zn2+ Precipitated in 0.1 M H2S solution at pH 9 Group IV: Ba2+, Ca2+, K+, Mg2+, Na+, NH4+ Ba2+, Ca2+, and Mg2+ are precipitated in 0.2 M (NH4)2CO3 solution at pH 10; the other ions are soluble Many reagents are used in qualitative analysis, but only a few are involved in nearly every group procedure. The four most commonly used reagents are 6M HCl, 6M HNO3, 6M NaOH, 6M NH3. Understanding the uses of the reagents is helpful when planning an analysis. Quantitative Analysis In chemistry, quantitative analysis is the determination of the absolute or
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