unknown 5a-5b - Ian Lieberman Scheme for Unknown SAISB...

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Unformatted text preview: Ian Lieberman Scheme for Unknown SAISB Possible Ions " , i) CationszNSf,K’, Nint‘oaf’, Mango 2*, maize),3+ ii)Anions: C1',NO3", sofi', HSO4‘, OH‘, (3032', HCO,‘ iii) Possible insoluble compounds: Ca(OH)2, CaSO42H20, CaC03, MgCOg, Mg(OI-l)2 Preparation before the unknown analysis: i) Prepare the "Neutral Water"; (P2—8) ii) Clean glassware and crucible, etc. iii) Get some indicators, reagents and litmus papers that you need use during the ‘ unknown analysis. Notes: 5A (the sample with the numerical label) is a pure salt, which means it only contains two (one cation and one anion) or three (alums, i.e., two cations and SO?) ions. Time limitation for SA/SB is 120 minutes. (Note: for an alum, one of the two cations Err—st be Al(HZO)63+, m be either NH; or Kl.) 1. Describe Sample: Phase, color, odor, crystal shape if crystalline, etc. 2. Test on Original Sample i) Flame Test Bushy yellow orange —> Na” (16’, NEH”, Ca2+, MgCHZO)52+, A1(H20)53+ possible) Red or red orange —> Ca2+ (No Na”: others maybe) Purple ——> K" (No Na+ and Ca2+, others maybe) No color a NHJ', Mg(H20) 2+, A1(HZO)53+ (No Nat, Ca2+, and K“) Notes: It is difficult to distinguish the color for Na+ and Ca2+ ions using solid samples, if you are not sure what color your sample have, you can usethe original solution y0u make, or the sample treated with 1M HCl to double check it, ii) NIL+ Test a) Place a small portion of original sample in a test tube or spot plate, then add a few drops of 1M NaOH solution, at then same time suspend a red litmus paper (before using it, you'd rinse it with deionized water) over the solution. If litmus paper turns blue, it means your sample has the Nth;+ ion. OF; 1)) Place a small portion of original sample in an open crucible, then heat it up. If continuous gray fumes and smoke are discharged, it means you have the NIL;+ ion. (Be careful, if you only see a little bit of green or yellow fumes come out, it is due to the moisture of your sample, not from NI-Lf’). iii) C032w and HCOs' Test 7 Place a little bit of original sample in the spot plate, and then treating with a few drops of 1M HC 1 , if odorless bubbles come out, it indicates the presence of C3032” or HCO3’. 3. Test pH Using a small portion of sample to make a solution with neutral water, and then test pH with indicators. ~22 6 H30; (No Hcogg (3032-, OH) ~3 to 3.5 —-> Ala—120)63+ (No H003”, coal", OH') ~5 to 6.0 —> NHL Mg(HzO)52+ ~7 —> c1", N03", 8042‘, 1C, Nat, Ca2+ ~85 a HCO; (No user, A1m20)63+, 0H) ~12 a» 0032“ (No HSO4', A1(HzO)63+, NH?) 213 —> 0H (No 3304: AI{H20)O3+, H003: Nun Notes: If your sample has an insoluble compound, you just use the saturated supernatant liquid to test pH. ‘ ' pH for insoluble compounds: Ca(OH)2: 42.6 (3380421120: CaCQ3; ~10g0 MgCO3: ~95 Mg(OH)3: ~10.5 4. Make Solution Dissolve 1/2 of sample with 10—1 SmL deionized water. i) For 5A, if sample is soluble, then use the solution to do cation and anion test (6). If insoluble, then just test the insoluble compound (5) and discard the supernatant liquid, ii) For 5B, if sample is soluble, then use the solution to test cation and anion (6). If it is insolubie, first you have to separate it using centrifuge, then use the supernatant liquid to test cation and anion (6), and also test the insoluble compound (5). 5. Test on Insoluble Compound CaCOEIh Red or red orange Flame test . "MEKUle " 'Ca(1")ii‘); ancoior I (3330321430 (321(1); 34ng Mgmli); Treat with 1M Hill Red or red orange Dissoit d {ECO-3 :e . i w . .. l. r A Bubbles '“Jl: mm P { M 1402)} No color Nothing 6. Test on Solution (or Supernatant Liquid) a) Cations (Flow Chart) Na’, [(2 NH; Cal2 p Mgr-Lop” ; mono)? E‘xeessfiM ML I Supernatant liquid . (3212’ Na“. NH: .. uperlimrmt liquid 4r . AKHgOthI‘I); l Mg(H20).i(0H}:(Sl Add 2M NaOl-l Excess saturated NHtCl Heating off NHL NH; 7 A ‘ Aliflzolaleiisl - E: fwd 6M IlAc N33CO(N02}5 ' Yellow ppt, K? Notes: "Excess" here is very important because you have to make sure that all of ions are separated completely, otherwise, it will interfere with your next specific test You should make sure that all of NHL}+ is gone before you test Kl. b) Anions i) CI' Acidify sample solution with 6M HNOg (stir the solution before you use the blue litmus paper to test it acidity) —> Adding few drops of 0.02M AgNO3 —> If white ppt formed, then (31' is present. ii) 303' Acidify sample solution with 6M l-INO3 (stir the retaliation before you use the blue lit-mus paper toAtest it acidity) ——> Adding few drops of 0.25M Ba(NO3)2 —> If white ppt formed, then 804" is present N037 Place a single crystal of Fe(H20)6(Nl—I4)2(SO4)Z in the hollow of a spot plate, then cover the crystal with few drops of the sample solution, and immediately two drops of 18M H2804 ——+ crystal turns brown, then N05 presented iv) H304“, OH'. C032} HCOg’: Tested before (Notes: if HSO4' ion presents, then just write down HSO4‘ (8042??) because so far we have not any method to decide whether we have 80421011 or not if H80; ion is presented). Hates: For 5A: Test'fiir 'SOf'ion FTRST'E For pI-l- for insoluble compound: use supernatant liquid For 5B: Soluble —> (Use Page 3 only! (Step 6)) Insoluble -+ (Use both charts (for cation chart, use supernatant liquid.) *Check 5B results with solubilitie's; ex. Co”, 3042' can’t be soluble (CaSO42HZO isn’t soluble!) SB: —> Completely Soluble —> Step 6 ——> Not Soluble (separate supernatant liquid) —-> Supernatant Liquid m) Step 6 we Insoluble Compound ~+ Step 5 (only one insolublecompound) ...
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This note was uploaded on 10/08/2009 for the course CHM 2046L taught by Professor Horvath during the Spring '08 term at University of Florida.

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unknown 5a-5b - Ian Lieberman Scheme for Unknown SAISB...

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