lab 7 report - The Separation and Identification of a Series of Cations
19 Pages

lab 7 report - The Separation and Identification of a Series of Cations

Course Number: CHEM 203, Fall 2009

College/University: University of Illinois,...

Word Count: 5249

Rating:

Document Preview

The Separation and Identification of a Series of Cations Yubo Liu Lab Partners: Leah, Dennis Due November 9th, 2009 Yubo Liu Abstract The object of this experiment was to familiarize with cations reaction with 11 reagents. Some trends were found based on research and observations. The acid reagents didnt generally form precipitates. The carbonate, phosphate, and chromate mostly formed precipitates and dissolved...

Unformatted Document Excerpt
Coursehero >> Illinois >> University of Illinois, Urbana Champaign >> CHEM 203

Course Hero has millions of student submitted documents similar to the one
below including study guides, practice problems, reference materials, practice exams, textbook help and tutor support.

Course Hero has millions of student submitted documents similar to the one below including study guides, practice problems, reference materials, practice exams, textbook help and tutor support.

Separation The and Identification of a Series of Cations Yubo Liu Lab Partners: Leah, Dennis Due November 9th, 2009 Yubo Liu Abstract The object of this experiment was to familiarize with cations reaction with 11 reagents. Some trends were found based on research and observations. The acid reagents didnt generally form precipitates. The carbonate, phosphate, and chromate mostly formed precipitates and dissolved in nitric acid test. Hydroxides of some cations were amphoteric. Some metals formed amine complexes. Sulfides precipitated with most cations in basic solutions were black. Sulfides did not precipitate well in acidic conditions. Introduction The goal of this experiment was to identify cations, which were positively charged ions, in known samples based on their reaction in certain reagent solutions through performing qualitative analysis. Since substances and ions have their unique set chemical properties, qualitative analysis can be used to determine these properties from a known sample. Using these identified properties, chemists could run series of tests on unknown samples and figure out what the contents are in the unknown sample. In this experiment, the main concerns were to identify and familiarize with the cations properties. 10 cations were tested on their chemical reactions with acids, bases, and anions. Qualitative analysis can have all kinds of tests. Five different tests were performed in the experiment. They were standard anion test, ammonia test, basic sulfide test, acidic sulfide test, and confirmatory test. In addition, the nitric test would be performed on those with precipitates to test for solubility in acids. Each of the cations would react differently to the combination of all the tests and illustrated through visible evidences. Observations were made and recorded into a chart. They would be useful to identify cations from an unknown sample later on. During these tests in the experiments, the cations exhibited different behaviors. Understandings of these behaviors were crucial to identifying their chemical properties. The first was that the some cations hydroxides precipitates were amphoteric: A(OH) (s) + H+ (aq) A+ (aq) + H2O (l) (1) A(OH) (s) + OH- (aq) A(OH)- (aq) (2) The cations hydroxide could be both acids and bases. Since some metal hydroxides could dissolve in excess hydroxide and acids, this test was useful to isolate the amphoteric species from those that were not. The second were cations behaviors in aqueous ammonia. When ammonia reacted with water, only a small percentage reacted to form ammonia and hydroxide. Four possible outcomes were possible when some cations came in contact in the solution: a metal hydroxide precipitate could form, an amine complex (a metal with many anions bonded) could form, a metal hydroxide precipitate could first and then dissolve into an amine complex, or no reaction could happen. M2+ + 4NH3 (aq) [M(NH3)4]2+ (aq) (3) Therefore, it was vital to keep a close watch on the well plates as the reactions ran. Another property could be determined based on what happened inside the solution. The third involved behaviors with sulfide ion, S2-, which was a weak acid: M2+ (aq) + S2- (aq) MS (s) (4) If [M2+][S2-] > Ksp Sulfide ion was used because the relative ease of control of its concentration. Depending on the solubility, a precipitate would form if the product of the concentrations of the reactants exceeds Yubo Liu Ksp. Since only certain cations could precipitate with sulfide ions, it was a useful procedure to separate cations. The last one involved in two ions, CO32- and PO43-, that acted as weak bases in solution: CO32- (aq) + H2O (l) HCO3- (aq) + OH- (aq) (5) PO43- (aq) + H2O (l) HPO42- (aq) + OH- (aq) (6) When these ions reacted with water, hydroxides were produced. As a result, hydroxide precipitate, carbonate or phosphate precipitate, hydrogen carbonate or phosphate precipitate, or mixture of all. Thus, this one was a bit more complicated than previous ones. Consequently, in addition to just mere observation, a series of detective works such as possible reactions considered and applying the observations to fit the possible reactions were needed to identify the cation from the observations. The identifications of specific ions such as lead are quite important in the food industry. The health department generally has regulations of certain ions to be contained. Qualitative analysis, through more advanced instruments, can help to check for harmful substances that might contaminate the food. Therefore, qualitative analysis is very important.1 Experimental Procedures The following were deviations from the lab manual. 2 1. More drops than the amount stated were used, but were not counted. 1 Julie L. Thies. Qualitative Analysis of Processes used by a Food Policy Council to Impact the Local Food System. http://apha.confex.com/apha/128am/techprogram/paper_10293.htm 2 University of Illinois Department of Chemistry, An Introduction to Chemical Systems I nthe Laboratory, 2007, 71-74 Results The sources used for research were all listed in the reference section Reagents 3 M HCl 6 M HNO3 3 M H2SO4 6 M HNO3 0.1 M Na3PO4 6 M HNO3 0.1 M Na2CO3 6 M HNO3 0.1 M K2CrO4 6 M HNO3 3 M NaOH 6 M HNO3 19 M NaOH 6 M HNO3 3 M NH3 or NH4OH 6 M HNO3 15 M NH3 or NH4OH 6 M HNO3 OH-/H2S 6 M HNO3 H+/H2S 6 M HNO3 Confirmation Test Reagents 3 M HCl 6 M HNO3 Pb2+ Pb2+ (aq) + 2Cl- (aq) PbCl2 (s) PbCl2 (s) + H+ (aq) No reaction Pb2+ (aq) + SO42- (aq) PbSO4 (s) PbSO4 (s) + H+ (aq) No reaction 3Pb2+ + 2PO43- Pb3(PO4)2 (s) Pb3(PO4)2 (s) + 6H+ (aq) 3Pb2+ (aq) + 6H+ (aq) + 2PO42- (aq) Pb2+ (aq) + CO32- (aq) Pb(CO3) (s) Pb(CO3) (s) + H+ (aq) Pb2+ (aq) + CO2 (g) + H2O (l) Pb2+ (aq) + CrO42- (aq) PbCrO4 (s) 2PbCrO4 (s) + 2H+ (aq) 2Pb2+ + Cr2O72- (aq) + H2O (l) Pb2+ (aq) + 2OH- (aq) Pb(OH)2 (s) Pb(OH)2 + 2H+ (aq) Pb2+ (aq) + 2H2O (l) Beginning: Pb2+ (aq) + 2OH- (aq) Pb(OH)2 (s) Excess NaOH: Pb(OH)2 (s) + 2OH- (aq) [Pb(OH)4]2- (aq) [Pb(OH)4]2- (aq) + 6H+ (aq) Pb(OH)2 (s) + 4H2O (l) Pb(OH)2 (s) +2H+ (aq) Pb2+ (aq) + 2H2O (l) Pb2+ (aq) + 2OH- (aq) Pb(OH)2 (s) Pb(OH)2 (s) +2H+ (aq) Pb2+ (aq) + 2H2O (l) Pb2+ (aq) + 2OH- (aq) Pb(OH)2 (s) Pb(OH)2 (s) +2H+ (aq) Pb2+ (aq) + 2H2O (l) Pb2+ (aq) + S2- (aq) PbS (s) Pb2+ (aq) + H2S (aq) PbS (s) + 2H+ (aq) 3PbS (s) + 2NO3 (aq) + 8H+ (aq) 3Pb2+ (aq) + 3S (s) + 2NO (g) + 4H2O (l) Pb2+(aq) + 2 I- (aq) PbI2 (s) (Yellow ppt.) PbI2 (s) + 2 I- (aq) PbI4- (aq) (Colorless solution) Ba2+ Ba2+ (aq) + 2Cl- (aq) No reaction Yubo Liu 3 M H2SO4 6 M HNO3 0.1 M Na3PO4 6 M HNO3 0.1 M Na2CO3 6 M HNO3 0.1 M K2CrO4 6 M HNO3 3 M NaOH 6 M HNO3 19 M NaOH Ba2+ (aq) + SO42- (aq) BaSO4 (s) BaSO4 (s) + H+ No reaction 3Ba2+ (aq) + PO43- (aq) Ba3(PO4)2 (s) Ba3(PO4)2 (s) + H+ 3Ba2+ (aq) + 3H+ (aq) + PO43- (aq) Ba2+ (aq) + CO32- (aq) BaCO3 (s) BaCO3 (s) + H+ (aq) Ba2+ (aq) + H2O (l) + CO2 (g) Ba2+ (aq) + CrO42-(aq) BaCrO4 (s) 2BaCrO4 (s) + 2H+ (aq) 2Ba2+ (aq) + Cr2O72- (aq) + H2O (l) Ba2+ (aq) + 2OH- (aq) Ba(OH)2 (s) Ba(OH)2 (s) + 2H+ (aq) Ba2+ (aq) + 2H2O (l) Ba2+ (aq) + 2OH- (aq) Ba(OH)2 (s) 6 M HNO3 3 M NH3 or NH4OH 6 M HNO3 15 M NH3 or NH4OH 6 M HNO3 OH-/H2S 6 M HNO3 H+/H2S 6 M HNO3 Confirmation Test Ba(OH)2 (s) + 2H+ (aq) Ba2+ (aq) + 2H2O (l) Ba2+ (aq) + NH3 (aq) No reaction Reagents 3 M HCl 6 M HNO3 3 M H2SO4 6 M HNO3 0.1 M Na3PO4 6 M HNO3 Ba2+ (aq) + NH3 (aq) No reaction S2- (aq) + Ba2+ (aq) No reaction (Decomposes) H2S (aq) + Ba2+ (aq) No reaction (Decomposes) Ba2+ (aq) + CrO42- (aq) BaCrO4 (s) (Yellow ppt.) Bi3+ Bi3+ (aq) + Cl- (aq) No reaction Bi3+ (aq) + SO42- (aq) No reaction Bi3+ (aq) + PO43+ (aq) BiPO4 (s) BiPO4 (s) + 3H+ (aq) Bi3+ (aq) + H3PO4 (aq) 0.1 M Na2CO3 6 M HNO3 0.1 M K2CrO4 6 M HNO3 3 M NaOH 6 M HNO3 19 M NaOH Bi3+ (aq) + CO32- (aq) Bi2(CO3)3 (s) Bi2(CO3)3 (s) + 6H+ (aq) 2Bi3+ (aq) + 3CO2 (g) + 3H2O (l) 2Bi3+ (aq) + CrO42- (aq) + 2H2O (l) (BiO)2(CrO4) (s) + 4H+ (aq) (BiO)2(CrO4) (s) + 4H+ (aq) 2Bi3+ (aq) + CrO42- (aq) + 2H2O (l) Bi3+ (aq) + 3OH- (aq) Bi(OH)3 (s) Bi(OH)3 (s) + 3H+ (aq) Bi3+ (aq) + 3H2O (l) Bi3+ (aq) + 3OH- (aq) Bi(OH)3 (s) 6 M HNO3 3 M NH3 or NH4OH 6 M HNO3 15 M NH3 or NH4OH 6 M HNO3 OH-/H2S 6 M HNO3 H+/H2S 6 M HNO3 Confirmation Test Bi(OH)3 (s) + H+ (aq) Bi3+ (aq) + 3H2O (l) Bi3+ (aq) + 3OH- (aq) Bi(OH)3 (s) Reagents 3 M HCl 6 M HNO3 3 M H2SO4 6 M HNO3 0.1 M Na3PO4 6 M HNO3 0.1 M Na2CO3 6 M HNO3 0.1 M K2CrO4 Bi(OH)3 (s) + H+ (aq) Bi3+ (aq) + 3H2O (l) Bi3+ (aq) + OH- (aq) Bi(OH)3 (s) Bi(OH)3 (s) + H+ (aq) Bi3+ (aq) + 3H2O (l) 2Bi3+ (aq) + 3S2- (aq) Bi2S3 (s) 2Bi3+ (aq) + 3H2S (aq) Bi2S3 (s) + 6H+ (aq) Bi2S3 (s) + 8H+ (aq) + 2NO3- (aq) 2Bi3+ (aq) + 2NO (g) + 4H2O (l) + 3S (s) Bi3+ (aq) + 3 I- (aq) BiI3 (s) (Green-black ppt.) BiI3 (s) + I- (aq) BiI4- (aq) (Orange Solution) Fe3+ Fe3+ (aq) + Cl- (aq) [FeCl]2+ (aq) Fe3+ (aq) + SO42- (aq) No reaction Fe3+ (aq) + PO42- (aq) FePO4 (s) FePO4 (s) + 3H+ (aq) Fe3+ (aq) + H3PO4 (aq) 2Fe3+ (aq) + 2CO32- (aq) + 3H2O (l) 2Fe(OH)3 (s) +2CO2 (g) Fe(OH)3 (s) + 3H+ (aq) Fe3+ (aq) + 3H2O (l) Fe3+ (aq) + CrO42- (aq) Fe2(CrO4)3 (s) Yubo Liu 6 M HNO3 3 M NaOH 6 M HNO3 19 M NaOH Fe2(CrO4)3 (s) + 2H+ (aq) 2Fe3+ (aq) + 3CrO42- (aq) + H2O (l) Fe3+ (aq) + 3OH- (aq) Fe(OH)3 (s) Fe(OH)3 (s) + 3H+ (aq) Fe3+ (aq) + 3H2O (l) Fe3+ (aq) + 3OH- (aq) Fe(OH)3 (s) 6 M HNO3 3 M NH3 or NH4OH 6 M HNO3 15 M NH3 or NH4OH 6 M HNO3 OH-/H2S Fe(OH)3 (s) + 3H+ (aq) Fe3+ (aq) + 3H2O (l) Fe3+ (aq) + 3OH- (aq) Fe(OH)3 (s) 6 M HNO3 H+/H2S 6 M HNO3 Confirmation Test Reagents 3 M HCl 6 M HNO3 3 M H2SO4 6 M HNO3 0.1 M Na3PO4 6 M HNO3 0.1 M Na2CO3 6 M HNO3 0.1 M K2CrO4 6 M HNO3 3 M NaOH 6 M HNO3 Fe(OH)3 (s) + 3H+ (aq) Fe3+ (aq) + 3H2O (l) Fe3+ (aq) + 3OH- (aq) Fe(OH)3 (s) Fe(OH)3 (s) + 3H+ (aq) Fe3+ (aq) + 3H2O (l) Fe3+ (aq) + HS- (aq) Fe2+ (aq) + S (s) + H+ (aq) Fe2+ (aq) + S2- (aq) FeS (S) Fe3+ (aq) + H2S (aq) Fe2+ (aq) + S (s) + 2H+ (aq) Fe2+ (aq) + H+ (aq) No reaction Fe3+ (aq) + SCN- (aq) Fe(SCN)2+ (aq) (Blood red solution) Fe3+ (aq) + K(Fe(CN)6)- (aq) KFe(Fe(CN)6) (s) (Royal blue ppt.) Mn2+ Mn2+ (aq) + 2Cl- (aq) No Reaction Mn2+ (aq) + SO42- (aq) No Reaction 3Mn2+ (aq) + 2PO43- (aq) Mn3(PO4)2 (s) Mn3(PO4)2 (s) + 6H+ (aq) 3Mn2+ (aq) + 2H3PO4 (aq) Mn2+ (aq) + CO32- (aq) Mn(CO3) (s) Mn(CO3) (s) + 2H+ (aq) Mn2+ (aq) + CO2 (aq) + H2O (l) Mn2+ (aq) + CrO42- (aq) MnCrO4 (s) MnCrO4 (s) + 4H+ (aq) Mn2+ (aq) + CrO42- (aq) + 2H2O (l) Mn2+ (aq) + 2OH- (aq) Mn(OH)2 (s) Mn(OH)2 (s) + 2H+ (aq) Mn2+ (aq) + 2H2O (l) 19 M NaOH Mn2+ (aq) + 2OH- (aq) Mn(OH)2 (s) 6 M HNO3 3 M NH3 or NH4OH 6 M HNO3 15 M NH3 or NH4OH 6 M HNO3 OH-/H2S 6 M HNO3 H+/H2S 6 M HNO3 Confirmation Test Mn(OH)2 (s) + 2H+ (aq) Mn2+ (aq) + 2H2O (l) Mn2+ (aq) + 2OH- (aq) Mn(OH)2 (s) Mn(OH)2 (s) + 2H+ (aq) Mn2+ (aq) + 2H2O (l) Mn2+ (aq) + 2OH- (aq) Mn(OH)2 (s) Mn(OH)2 (s) + 2H+ (aq) Mn2+ (aq) + 2H2O (l) Mn2+ (aq) + S2- (aq) MnS (s) Mn2+ (aq) + S2- (aq) No Reaction 2Mn2+(aq) + 5BiO3-(aq) + 14H+(aq) 2MnO4-(aq) + 5BiO+(aq) + 7H2O(l) Ag+ Ag+ (aq) + Cl- (aq) AgCl (s) AgCl (s) + H+ (aq) no reaction Ag+ (aq) + SO42- (aq) No Reaction Reagents 3 M HCl 6 M HNO3 3 M H2SO4 6 M HNO3 0.1 M Na3PO4 6 M HNO3 0.1 M Na2CO3 6 M HNO3 0.1 M K2CrO4 6 M HNO3 3 M NaOH 6 M HNO3 19 M NaOH 3 Ag+ (aq) + PO43- (aq) Ag3PO4 (s) Ag3PO4 (s) + 3H+ (aq) Ag+ (aq) + H3PO4 (aq) 2Ag+ (aq) + CO32- (aq) Ag2O (s) + CO2 (g) Ag2O (s) + 2H+ (aq) 2Ag+ (aq) + H2O (l) Ag+ (aq) + CrO42- (aq) Ag2CrO4 (s) 2Ag2CrO4 (s) + 2H+ (aq) 4Ag+ (aq) + Cr2O72- (aq) + H2O (l) 2Ag+ (aq) + 2OH- (aq) Ag2O (s) + H2O (l) Ag2O (s) + 2H+ (aq) 2Ag+ (aq) + H2O (l) 2Ag+ (aq) + 2OH- (aq) Ag2O (s) + H2O (l) 6 M HNO3 Ag2O (s) + 2H+ (aq) 2Ag+ (aq) + H2O (l) Yubo Liu 3 M NH3 or NH4OH 6 M HNO3 15 M NH3 or NH4OH 6 M HNO3 OH-/H2S 6 M HNO3 H+/H2S 6 M HNO3 Confirmation Test Reagents 3 M HCl 6 M HNO3 3 M H2SO4 6 M HNO3 0.1 M Na3PO4 6 M HNO3 0.1 M Na2CO3 6 M HNO3 0.1 M K2CrO4 6 M HNO3 3 M NaOH 6 M HNO3 19 M NaOH 6 M HNO3 3 M NH3 or NH4OH 6 M HNO3 15 M NH3 or 2Ag+ (aq) + 2OH- (aq) Ag2O (s) + H2O (l) Ag2O (s) + 2H+ (aq) 2Ag+ (aq) + H2O (l) 2Ag+ (aq) + 2OH- (aq) Ag2O (s) + H2O (l) Excess: Ag2O (s) + 4NH3 (aq) + H2O (l) 2[Ag(NH3)2]+ (aq) + 2OH- (aq) [Ag(NH3)2]+ (aq) + 2H+ (aq) Ag+ (aq) + 2NH4+ (aq) 2Ag+ (aq) + S2- (aq) Ag2S (s) 2Ag+ (aq) + H2S (aq) Ag2S (s) + 2H+ (aq) 3Ag2S (s) + 8H+ (aq) + 2NO3- (aq) 6Ag+ (aq) + 2NO (aq) + 4H2O (l) + 3S(s) Ag+ (aq) + I- (aq) AgI (s) (Light-yellow ppt.) Cu2+ Cu2+ (aq) + 2Cl- (aq) No reaction Cu2+ (aq) + SO42- (aq) no reaction Cu2+ (aq) + PO43- (aq) Cu3(PO4)2 (s) Cu3(PO4)2 (s) +3H+ (aq) Cu2+ + H3PO4 (aq) Cu2+ (aq) + CO32- (aq) CuCO3 (s) CuCO3 (s) + 2H+ (aq) Cu2+ (aq) + CO2 (g) + H2O (l) Cu2+ (aq) + CrO42- (aq) CuCrO4 (s) 2CuCrO4 (s) + 2H+ (aq) Cu2+ (aq) + Cr2O72- (aq) + H2O (l) Cu2+ (aq) + OH- (aq) Cu(OH)2 (s) Cu(OH)2 (s) + H+ (aq) Cu2+ (aq) + 2H2O (l) Cu2+ (aq) + OH- (aq) Cu(OH)2 (s) Excess: Cu(OH)2 (s) + 2OH- (aq) [Cu(OH)4]2- (aq) Cu(OH)2 (s) + heat CuO (s) + H2O (l) Cu2+ (aq) + OH- (aq) Cu(OH)2 (s) Cu(OH)2 (s) + H+ (aq) Cu2+ (aq) + 2H2O (l) Cu2+ (aq) + OH- (aq) Cu(OH)2 (s) NH4OH 6 M HNO3 OH-/H2S 6 M HNO3 H+/H2S 6 M HNO3 Confirmation Test Reagents 3 M HCl 6 M HNO3 3 M H2SO4 6 M HNO3 0.1 M Na3PO4 6 M HNO3 0.1 M Na2CO3 6 M HNO3 0.1 M K2CrO4 6 M HNO3 3 M NaOH 6 M HNO3 19 M NaOH 6 M HNO3 3 M NH3 or NH4OH 6 M HNO3 15 M NH3 or NH4OH 6 M HNO3 OH-/H2S 6 M HNO3 Excess: Cu2+ (aq) + 4NH3 (aq) [Cu(NH3)4]2+ (aq) [Cu(NH3)4]2+ (aq) + 4H+ (aq) Cu2+ (aq) + 4NH4+ (aq) Cu2+ (aq) + S2- (aq) CuS (s) Cu2+ (aq) + H2S (aq) CuS (s) + H+ (aq) 3CuS (s) + 8H+ (aq) + 2NO3- (aq) 3Cu2+ (aq) + 2NO (g) + 4H2O (l) + 3S(s) Cu2+ (aq) + I- (aq) CuI2 (s) (Tan ppt. and orange solution) 2 Cu 2+ (aq) + (Fe(CN)6)4- (aq) Cu2[Fe(CN)6] (s) (Red/brown ppt.) Ni2+ Ni (aq) + Cl (aq) No reaction 2+ - Ni2+ (aq) + SO42- (aq) no reaction Ni2+ (aq) + PO43- (aq) Ni3(PO4)2 (s) Ni3(PO4)2 (s) + 6H+ (aq) 3Ni2+ (aq) + 2H3PO4 (aq) Ni2+ (aq) + CO32- (aq) NiCO3 (s) NiCO3 (s) + 2H+ (aq) Ni2+ (aq) + CO2 (g) + H2O (l) Ni2+ (aq) + CrO42- (aq) NiCrO4 (s) 2NiCrO4 (s) + 2H+ (aq) 2Ni2+ (aq) + Cr2O72- (aq) + H2O (l) Ni2+ (aq) + OH- (aq) Ni(OH)2 (s) Ni(OH)2 + (s) 2H+ (aq) Ni2+ (aq) + 2H2O (l) Ni2+ (aq) + OH- (aq) Ni(OH)2 (s) Ni(OH)2 (s) + 2H+ (aq) Ni2+ (aq) + 2H2O (l) Ni2+ (aq) + OH- (aq) Ni(OH)2 (s) Ni(OH)2 (s) + 2H+ (aq) Ni2+ (aq) + 2H2O (l) Ni2+ (aq) + 6NH3 (aq) [Ni(NH3)6]2+ (aq) [Ni(NH3)6]2+ (aq) + 6H+ (aq) Ni2+ (aq) + 6NH4+ (aq) Ni2+ (aq) + S2- (aq) NiS (s) Yubo Liu H+/H2S 6 M HNO3 Confirmation Test Reagents 3 M HCl 6 M HNO3 3 M H2SO4 6 M HNO3 0.1 M Na3PO4 6 M HNO3 0.1 M Na2CO3 6 M HNO3 0.1 M K2CrO4 6 M HNO3 3 M NaOH 6 M HNO3 19 M NaOH 6 M HNO3 3 M NH3 or NH4OH 6 M HNO3 15 M NH3 or NH4OH 6 M HNO3 OH-/H2S 6 M HNO3 H+/H2S Ni2+ (aq) + H2S (aq) No reaction Ni2+ (aq) + 2 DMG- (aq) Ni(DMG)2 (s) (Strawberry red ppt.) Zn2+ Zn2+ (aq) + Cl- (aq) No reaction Zn2+ (aq) + SO42- (aq) No reaction Zn2+ (aq) + PO43- (aq) Zn3(PO4)2 (s) Zn3(PO4)2 (s) + 6H+ (aq) 3Zn2+ (aq) + 2H3PO4 (aq) Zn2+ (aq) + CO32- (aq) ZnCO3 (s) ZnCO3 (s) + 2H+ (aq) Zn2+ (aq) + H2O (l) + CO2 (l) Zn2+ (aq) + CrO42- (aq) ZnCrO4 (s) 2ZnCrO4 (s) + 2H+ (aq) Zn2+ (aq) + Cr2O72- (aq) + H2O (l) Zn2+ (aq) + 2OH- (aq) Zn(OH)2 (s) Zn(OH)2 (s) + 2H+ (aq) Zn2+ (aq) + 2H2O (l) Zn2+ (aq) + 2OH- (aq) Zn(OH)2 (s) Excess: Zn(OH)2 (s) + 2OH- (aq) [Zn(OH)4]2- (aq) [Zn(OH)4]2- (aq) + 4H+ (aq) Zn(OH)2 (s) + 4H2O (l) Zn(OH)2 (s) + 2H+ (aq) Zn2+ (aq) + 2H2O (l) Zn2+ (aq) + OH- (aq) Zn(OH)2 (s) Zn(OH)2 (s) + 2H+ (aq) Zn2+ (aq) + 2H2O (l) Zn2+ (aq) + OH- (aq) Zn(OH)2 (s) Zn(OH)2 (aq) + 4NH3 (aq) [Zn(NH3)4]2+ (aq) + 2OH- (aq) [Zn(NH3)4]2+ (aq) + 4H+ (aq) Zn2+ (aq) + 4NH4+ (aq) Zn2+ (aq) + S2- (aq) ZnS (s) Zn2+ (aq) + H2S (aq) No reaction 6 M HNO3 Confirmation Test Reagents 3 M HCl 6 M HNO3 3 M H2SO4 6 M HNO3 0.1 M Na3PO4 6 M HNO3 0.1 M Na2CO3 6 M HNO3 0.1 M K2CrO4 6 M HNO3 3 M NaOH 6 M HNO3 19 M NaOH 6 M HNO3 3 M NH3 or NH4OH 6 M HNO3 15 M NH3 or NH4OH 6 M HNO3 OH-/H2S 6 M HNO3 H+/H2S 6 M HNO3 Confirmation Test Zn2+ (aq) + S2- (aq) ZnS (s) (White ppt.) Al3+ Al3+ (aq) + Cl- (aq) No reaction Al3+ (aq) + SO42- (aq) no reaction Al3+ (aq) + PO43- (aq) AlPO4 (s) AlPO4 (s) + 3H+ (aq) Al3+ (aq) + H3PO4 (aq) 2Al3+ (aq) + 3CO32- + 3H2O (l) 2Al(OH)3 (s) + 3CO2 (g) Al(OH)3 (s) + 2H+ (aq) Al3+ (aq) + 2H2O (l) Al3+ (aq) + CrO42- (aq) Al2(CrO4)3 (s) 2Al2(CrO4)3 (s) + 6H+ (aq) 4Al3+ (aq) + 3Cr2O72- (aq) + 3H2O (l) Al3+ (aq) + OH- (aq) Al(OH)3 (s) Al(OH)3 (s) + H+ (aq) Al3+ (aq) + H2O (l) Al3+ (aq) + OH- (aq) Al(OH)3 (s) Al(OH)3 (s) + OH- (aq) AlO2- (aq) + H2O (l) Al(OH)3 (s) + H+ (aq) Al3+ (aq) + H2O (l) Al3+ (aq) + OH- (aq) Al(OH)3 (s) Al(OH)3 (s) + H+ (aq) Al3+ (aq) + H2O (l) Al3+ (aq) + OH- (aq) Al(OH)3 (s) Al(OH)3 (s) + 6NH3 (aq) [Al(NH)6]3+ (aq) + 3OH- (aq) [Al(NH)6]3+ (aq) + 6H+ (aq) Al3+ (aq) + 6NH4+ (aq) Al3+ (aq) + S2- (aq) No reaction (decomposes) Al3+ (aq) + H2S (aq) No reaction (decomposes) Al3+ (aq) + OH- (aq) Al(OH)3 (s) Al(OH)3 (s) + 3 H+ (aq) Al3+ (aq) + 3 H2O (l) Al3+ (aq) + Aluminon Al(OH)3 (s) (Ppt. dyed red due to absorption of aluminon) Yubo Liu Pb2+ 3 M HCl/ 6 M HNO3 3 M H2SO4 /6 M HNO3 0.1 M Na3PO4 /6 M HNO3 Ba2+ Bi3+ Fe3+ Mn2+ White ppt. / no reaction No reaction No reaction Yellow solution No reaction Milky white solution, ppt / solution cleared ppt. remained Light blue ppt. / ppt. dissolved Milky white solution, ppt/ No reaction No reaction No reaction No reaction Light blue ppt. / Ppt. dissolve Milky white solution, ppt / no reaction Cloudy white ppt. cleared yllow after time / turned clear Brown ppt, orange solution after time / solution cleared, ppt dissolved, bubbles Orange solution / no reaction Cloudy white solution, ppt / solution cleared, ppt dissolved Brown ppt. / no reaction Cloudy tan solution, white ppt / no reaction 0.1 M Na2CO3 /6 M HNO3 Milky white ppt. slight bubbling. / ppt dissolved Milky white solution, ppt / solution cleared, bubbling, ppt. dissolved White ppt, bubbling / no reaction 0.1 M K2CrO4 /6 M HNO3 Cloudy yellow solution, white ppt. / no reaction Milky yellow solution, ppt / solution cleared, ppt dissolved 3 M NaOH / 6 M HNO3 White ppt formed but then dissolved / same as above White ppt formed but then dissolved / same as above White powderish ppt / no reaction Light blue/white ppt / ppt. dissolved Yellow solution with yellow ppt. / solution cleared, ppt dissolved White ppt. / dissolved 19 M NaOH / 6 M HNO3 3 M NH3 or NH4OH/ 6 M HNO3 15 M NH3 or NH4OH/ 6 M HNO3 OH-/H2S/ 6 M HNO3 Not White ppt. / clear solution, ppt dissolved, bubbles Orange yellow solution / no reaction Trace amount of white ppt. / ppt dissolved White ppt / no reaction Dark brown ppt / no reaction Cloudy tan solution, white ppt / no reaction No reaction White ppt. / ppt dissolved Brown ppt. yellow solution / ppt dissolved White ppt. / dissolved White ppt. / mostly dissolved No reaction White ppt. mostly dissolved Slight brown solution / no reaction Black and silver ppt, possible yellow solution Yellow solution Black and silver ppt. possible yellow solution Brown ppt. solution kind of yellow / ppt dissolved, yellow solution Black and silver ppt. possible yellow solution Milky yellow solution, white ppt performed H+/H2S/ 6 M HNO3 0.1 M Na2CO3 /6 M HNO3 No reaction Black and silver ppt. / no reaction Cloudy solution, white ppt / no reaction No reaction Ag+ 3 M HCl/ 6 M HNO3 3 M H2SO4 /6 M HNO3 0.1 M Na3PO4 /6 M HNO3 Black solution, silver ppt. / black solution, ppt dissolved Cu2+ Ni2+ Zn2+ Al3+ White ppt / no reaction No reaction No reaction No reaction No reaction No reaction No reaction No reaction No reaction No reaction Cloudy yellow, ppt / solution cleared, ppt dissolved Very light solution, white ppt / ppt dissolved, solution cleared Blue solution, white ppt / solution cleared, ppt dissolved, bubbles Muddy yellow solution, yellow ppt. / ppt. dissolved, yellow solution Blue solution, cloudy blue pt. / clear solution, blue ppt remained Blue ppt. / clear solution, brown ppt. Cloudy solution, white ppt / ppt dissolved, solution cleared Very light blue ppt / ppt dissolved White ppt. / ppt dissolved Cloudy solution, white ppt / ppt dissolved, clear solution, bubbles Milky solution, white ppt. / ppt. dissolved, clear solution, bubbles White ppt, orange solution / no reaction Yellow solution / darker yellow solution Yellow solution / darker yellow solution White ppt, orange solution / no reaction Green cloudy ppt. / dissolved, clear solution Faint cloudy ppt. / no reaction Slight white ppt. / no reaction Green cloudy solution, green ppt. / no reaction Some cloudy white ppt. / no reaction Royal blue solution / solution turned clear Dark blue solution / solution cleared Light blue ppt. / ppt. dissolved No reaction White ppt / tan or yellow ppt, very light solution Yellow solution / turned orange or peach Light blue solution / solution cleared No reaction Yellow solution / solution turned orange or peach Yellow solution, black silver ppt Yellow solution, black silver ppt. Black and silver ppt. Yellow solution, faint white specks Orange yellow solution Silver black ppt. / silver ppt dissolved completely, Black silver ppt. / silver ppt, solution cleared No reaction No reaction Peach colored solution / no reaction White ppt. / ppt. dissolved, bubbles 0.1 M K2CrO4 Dark brown ppt / ppt. dissolved, /6 M HNO3 yellow solution 3 M NaOH / 6 M HNO3 Tan ppt./ ppt. dissolved, solution turned clear 19 M NaOH / 6 M HNO3 Dark tan ppt. / white ppt and solution 3 M NH3 or NH4OH/ 6 M HNO3 White ppt / no reaction 15 M NH3 or NH4OH/ 6 M HNO3 OH-/H2S/ 6 M HNO3 Not performed H+/H2S/ 6 M HNO3 White ppt / no reaction Yubo Liu solution kinda brown, black ppt remained Discussion The goal of this experiment was to familiarize with the 10 cations and their reactions with the reagents. Each of the 10 cations had their unique set of properties, which meant that no two cations reacted with the reagents exactly the same way. This paved the way for the next experiment, which would be qualitative analysis. The cations in an unknown solution would be separated and identified based on the qualitative observations from this experiment. In this experiment, the concerns lied only with the testing and knowing the 10 cations. Besides the 11 reagents used, there were also nitric acid tests and confirmatory test. Whenever a reaction had a precipitate or drastic color change, nitric acid test was added to the sample. Most of the precipitates were found to be soluble in acids except precipitate formed with strong acid reagents. The confirmatory test was used to test and confirm the existence of a certain cation inside a solution. The confirmatory tests were not used for qualitative analysis directly. But knowing the observations of the test would help in identifying cations of an unknown solution in next weeks and future experiment. Since the observations were all qualitative, some did not match with the theoretical reactions that took place. To account for the discrepancies, there were two reasons. One was that the qualitative observations were not correct; the other was that the chemical reactions were not correct. In this experiment, the majority of the discrepancies were due to the first reason. Most of the incorrect observations came from sodium hydroxides and aqueous ammonia. The main cause was that the concentration of these two reagents played key roles in the way the cations reacted. In the actual experiment, the amount of cation and reagents varied each trial. Because some of the cation hydroxides dissolved or formed complexes with excess ammonia or sodium hydroxides, the excess 3 molar reagents may have pushed the cation hydroxides to dissolve or form complexes. As a result, the reaction exhibited differed for the sodium hydroxide and ammonia reagents. There were 11 reagents, in addition to the addition of nitric acid test. Several trends were concluded after observing and researching the reactions. The first one was that hydrochloric acid and sulfuric acid generally didnt precipitate with the cations except lead, barium, and silver. The precipitates formed were of white color, and they had very low solubility constants and were insoluble in water and nitric acid. The second trend was that the cations formed precipitate with phosphate and carbonate as metal phosphates, metal carbonates, or metal hydroxides. That meant that they were insoluble in water, but they were readily soluble after the nitric acid test. Also, carbon dioxide gas was released in every carbonate reaction. Trends with chromate were similar. Precipitate was formed in all the reaction, and the precipitate was generally yellow to brown color. Cations like bismuth and aluminum reacted with chromate to form unsuspected precipitates. However, they still acted like the rest. In hydroxides, the trends were not as clear cut. The precipitates all dissolved in nitric acid. But some were soluble before the nitric acid test. The trend could be seen as whether or not the metal hydroxide was amphoteric, which meant having the ability to dissolve in acid and basic solution. Lead, copper, zinc, and aluminum hydroxides were all amphoteric. It meant that the when hydroxide precipitates were emerged in too much sodium hydroxide, the precipitate dissolved again. In aqueous ammonia, similar trends happened as hydroxides. But instead, the excess ammonia pushed the precipitate to form amine complexes, which were aqueous solutions Yubo Liu of metals with ammonia as ligands. The formation of these complexes usually meant that the solution were colored (or colorless as in the case of the amine complex of nickel), which meant relative ease to identify. With the sulfides, the basic and acidic sulfide differed. In the basic sulfide, cations generally formed black precipitate with the exceptions of barium and aluminum, which decomposed in water. The nitric acid test was not performed on any basic sulfides due to safety concerns. In acidic conditions, only lead, bismuth, silver, and copper formed precipitate. They all dissolved in nitric acid and formed elemental sulfur and gave off nitrogen oxide. The rest either had no reaction or decomposed in water. The difference in the precipitation under the two conditions was due to that in basic solution, the sulfide ion existed mostly as S2-, which reacted readily. In acidic solution, the sulfide ion existed mostly as H2S, which reacted less readily. The lab was successful. Most of the observations corresponded to the theoretical chemical equations from research. However since the goal of this experiment was observe the reactions qualitatively, the majority were correct, thus it was successful. These observations would be very helpful in a qualitative analysis of unknown cation solution. That experiment would be next week. So this experiment was extremely crucial for future references. References Julie L. Thies. Qualitative Analysis of Processes used by a Food Policy Council to Impact the Local Food System. http://apha.confex.com/apha/128am/techprogram/paper_10293.htm University of Illinois Department of Chemistry, An Introduction to Chemical Systems I nthe Laboratory, 2007, 7174 http://www.ausetute.com.au/solrules.html http://genchem.chem.wisc.edu/lab/cca/MAIN/NAOH/PAGE1.HTM http://www.chemguide.co.uk/inorganic/group4/lead.html https://www.mcla.edu/Undergraduate/uploads/textWidget/1712.00001/documents/Section_11.pdf http://chemlab.truman.edu/CHEM121Labs/QualAnalysis.htm http://www.bpreid.com/cations.php Solubility Chart. Section 8: Analytical Chemistry. CRC Handbook of Chemistry and Physics http://www.hbcpnetbase.com/ Treadwell, Frederick. Analytical chemistry, Volume 1. http://books.google.com/books? id=ubuaqKkwsQoC&pg=PA197&lpg=PA197&dq=solubility+of+zinc+sulfide+in+acid&s ource=bl&ots=7udbps1NcZ&sig=Os9qmMCEm4FfNEnADaHJKCgMP4&hl=en&ei=CHz3SuPaOorQM8jw_OgF&sa=X&oi=book_result&ct=result&resn um=7&ved=0CCoQ6AEwBg#v=onepage&q=solubility%20of%20zinc%20sulfide%20in %20acid&f=false Yubo Liu
MOST POPULAR MATERIALS FROM CHEM 203
MOST POPULAR MATERIALS FROM CHEM
MOST POPULAR MATERIALS FROM University of Illinois, Urbana Champaign