NSCI 1332 Study Guide - Final Guide: Flame Test, Watch Glass, Sodium Hydroxide
10 Sep 2015
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Tested an unknown to determine cations that were present. Clean wire with hcl and burn then add the solution to the wire and do the flame test. Place a watch glass with red litmus (moist with distilled water), turns blue. Add nh3 and nh4cl, precipitate forms that may contain iron, aluminum and chromium. Add naoh and h2o2, some precipitate dissolves (aluminum and chromium dissolve) Add hcl to the rust colored precipitate that is left, precipitate dissolves. Add aluminon reagent and nh3, precipitate giving red lake forms. 3+ +3 nh 3+3h 2 o+aluminon al (oh)3( s)( lake)+3 nh 4. Add naoh to precipitate out nickel and magnesium leaves zinc in supernatant. Add hcl and k4[fe(cn)6] to the x, gray-blue precipitate forms. 4 zn3 k 2[ fe (cn )6]2(s )+12h2 o. Dissolve precipitate (ni(oh)2) in nh3, pale violet decantate forms. 2+ +2 hc4 h 7 n 2o2 (c4 h 7 n 2o2)2(s)+4 nh3+2nh4. Add magnesium reagent and naoh, blue lake forms.
