Instruction for unknown 9A

Instruction for unknown 9A - bubbles appear CO32 or HCO3 is...

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Scheme for unknown 9A/9B Possible ions: 1. Cations : Na+, K+, NH4+, Ca 2+, Mg(OH2)6 2+, Al(OH2)6 3+ Zn(OH2)6 2+, Ag(OH2)2+ , Cu(OH2)6 2+ 2. Anions : OH-, CO3 2-, HCO3-, SO4 2-, HSO4-, NO3-, Cl-, HS-, O2- 3. Possible insoluble substances : Ca(OH)2, CaSO4•2H2O, CaCO3, MgCO3, Mg(OH)2 AgCl, Ag2O, Ag2CO3, Ag2S, Ag2SO4, ZnS, ZnCO3, Zn(OH)2, CuO, CuS, CuCO3 4. Alums Notes: --9A is a pure salt , which means it only contains two (one cation and one anion) or three ( alums , i.e., two cations and SO42−) ions. -- The insoluble substance could be one or more kinds of the above compounds. Zn(OH)2/ ZnS will not be in the same sample, nor would a MgCO3/ Mg(OH)2 be issued. Tests on original sample 1. Flame - Yellow-orange: Na+ - Red-orange: Ca2+ - Purple: K+ - Green: Cu(OH2)62+ - None: NH4+, Mg(OH2)2+, Al(OH2)3+, Zn(OH2)2+, Ag(OH2)2+ 2. NH4+ Test - Place small sample in test tube, add 1 M (or 6M) NaOH, suspend damp red litmus over it, if it turns blue, NH4+ is present 3. CO32-/HCO3- Test - Place original sample in a spot plate and add a few drops of 1M HNO3, if colorless
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Unformatted text preview: bubbles appear, CO32- or HCO3- is present 4 S2-/HS- Test - Place original sample in a spot plate and add a few drops of 2M H2SO4, if a rotten egg smell w/ bubbles, then S2- or HS- is present Make solution 4. Make Solution For A, Dissolve 1/4 of sample with 5 mL deionized water; for B, dissolve of sample with 10mL deionized water i) For 9A , if sample is soluble, then use the solution to do cation and anion test. If insoluble, then just test the insoluble compound and also save the supernatant liquid. ii) For 9B , if sample is soluble, then use the solution to test cation and anion. If it is insoluble, first you have to separate it using centrifuge, then use the supernatant liquid to test cation and anion and also test the insoluble compound. pH test should be done with the clear supernatant with indicator when sample is insoluble, pH paper is not sensitive enough for insoluble compounds....
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This note was uploaded on 02/08/2012 for the course CHM 2046L taught by Professor Horvath during the Spring '08 term at University of Florida.

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Instruction for unknown 9A - bubbles appear CO32 or HCO3 is...

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