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ERIC Number: EJ829100
Record Type: Journal
Publication Date: 2008-Aug
Pages: 3
Abstractor: As Provided
ISSN: ISSN-0021-9584
Greener Alternative to Qualitative Analysis for Cations without H[subscript 2]S and Other Sulfur-Containing Compounds
Sidhwani, Indu Tucker; Chowdhury, Sushmita
Journal of Chemical Education, v85 n8 p1099-1101 Aug 2008
Qualitative analysis of inorganic salts and mixtures is an essential experiment carried out in high school, undergraduate, and postgraduate levels all over the world especially in India and South Asia. The classical technique uses H[subscript 2]S, which is highly toxic and has adverse effects on humans and the environment. Increasing awareness concerning a healthy environment has prompted us to develop a green scheme for detection of cations. NH[subscript 4] [superscript +] and K[superscript +] are detected directly in group zero. Pb[superscript 2+] and Ag[superscript +] are detected in group I as chlorides using dilute HCl. Ca[superscript 2+], Sr[superscript 2+], Ba[superscript 2+], and Pb[superscript 2+] are precipitated in group II as sulfates using Na[subscript 2]SO[subscript 4](aq) and ethanol. Cu[superscript 2+], Cd[superscript 2+], Fe[superscript 3+], Mn[superscript 2+], Co[superscript 2+], Ni[superscript 2+], and Mg[superscript 2+] are precipitated as hydroxides using NaOH and H[subscript 2]O[subscript 2] in group III. The precipitate is treated with NH[subscript 3](aq) leaving a residue (group IIIA: Fe[superscript 3+], Mn[superscript 2+], Mg[superscript 2+] as hydroxides) and the centrifugate (group IIIB: Cu[superscript 2+], Cd[superscript 2+], Ni[superscript 2+], Co[superscript 2+] as soluble ammines). Al[superscript 3+], Zn[superscript 2+], Sn[superscript 2+]/Sn[superscript 4+] (as soluble hydroxo complexes), and Cr[superscript 3+] (as CrO[subscript 4][superscript 2-]) are detected in group IV, in the presence of each other by using selective reagents. The separation is sharp; individual cations are detected by spot tests and conventional methods. This scheme is simple and fast and makes green chemistry accessible to students. (Contains 1 table.)
Division of Chemical Education of the American Chemical Society. Subscription Department, P.O. Box 1267, Bellmawr, NJ 08099-1267. Tel: 800-691-9846; Tel: 856-931-5825; Fax: 856-931-4115; e-mail:; Web site:
Publication Type: Journal Articles; Reports - Descriptive
Education Level: Higher Education
Audience: Teachers
Language: English
Sponsor: N/A
Authoring Institution: N/A
Identifiers - Location: Asia; India