Mystery of the 14 test tubes. There are 14 different tubes. To identify the cont

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Mystery of the 14 test tubes. There are 14 different tubes.
To identify the contents of 14 different test tubes using afew simple tests and thir mutual reactivities. This experiement isuseful where the standard qualitive anaylsis scheme is notused. 1. H2SO4 2. NaCl 3. KNO3 4. SnCl2 5. NH3 6. Fe(NO3)3 7. Cu(NO3)2 8. KSCN 9. K2CrO4 10. K2C2O4 11. NiSO4 12. Ba(NO3)2 13. Na2S 14. H2O One of the TA's, we don't know who, has filled 14 test tubeswith 14 different solutions and labeled them with a secret code.The actual identity of each solution is a mystery. you are the chemical detective. you must correctly identifyeach solution. (PH test and flame test are also avaliable) Question!! 1)A favorite trick of graduate assistants is to give a studenta test tube which contains only distilled water. If you suspectedthat one of your test tubes was plain water, how might you testthat theory? 2)Give an example of a chemical reagent, not on the list ofsuspects, which might have made the identification of NaCleasier? 3)If lead (Pb2+)were added as a fifteen solution, whatreactions would you observe? (please give me good explanation) To identify the contents of 14 different test tubes using afew simple tests and thir mutual reactivities. This experiement isuseful where the standard qualitive anaylsis scheme is notused. 1. H2SO4 2. NaCl 3. KNO3 4. SnCl2 5. NH3 6. Fe(NO3)3 7. Cu(NO3)2 8. KSCN 9. K2CrO4 10. K2C2O4 11. NiSO4 12. Ba(NO3)2 13. Na2S 14. H2O One of the TA's, we don't know who, has filled 14 test tubeswith 14 different solutions and labeled them with a secret code.The actual identity of each solution is a mystery. you are the chemical detective. you must correctly identifyeach solution. (PH test and flame test are also avaliable) Question!! 1)A favorite trick of graduate assistants is to give a studenta test tube which contains only distilled water. If you suspectedthat one of your test tubes was plain water, how might you testthat theory? 2)Give an example of a chemical reagent, not on the list ofsuspects, which might have made the identification of NaCleasier? 3)If lead (Pb2+)were added as a fifteen solution, whatreactions would you observe? (please give me good explanation) 13. Na2S 14. H2O One of the TA's, we don't know who, has filled 14 test tubeswith 14 different solutions and labeled them with a secret code.The actual identity of each solution is a mystery. you are the chemical detective. you must correctly identifyeach solution. (PH test and flame test are also avaliable) Question!! 1)A favorite trick of graduate assistants is to give a studenta test tube which contains only distilled water. If you suspectedthat one of your test tubes was plain water, how might you testthat theory? 2)Give an example of a chemical reagent, not on the list ofsuspects, which might have made the identification of NaCleasier? 3)If lead (Pb2+)were added as a fifteen solution, whatreactions would you observe? (please give me good explanation)

Explanation / Answer

1. If one suspects that the test tube had plain water,then as plain water has some amount of dissolved salts like NaCl.So, the test tube is tested for the presance of Chlorides.For testing the presance of chloride, a solution ofAgNO3 is employed which would produce a whiteprecipitate of AgCl(s) in slightly acidic conditions. Simply, a pH test would also serve the purpose. The pHof distilled water is 7. If the pH of the solution is not shownaround 7, the then the water is not distilled water. 2. The chemical reagent used for the identification ofNaCl is aqueous AgNO3. The solution is initiallyacidified using dilute HNO3 and then aqueousAgNO3 solution is added. If a white precipitate appearsthen the solution is NaCl                                            AgNO3(aq) + NaCl (aq)     AgCl (s) + Na+ +NO3+ 3. If Pb+2solution is taken in a test tube, thetests it would respond to are with K2CrO4 itwould give a yellow precipitate of PbCrO4(s)      Pb+2 +K2CrO4   PbCrO4(s) + 2 K+ It also gives a white precipitate of PbCl2with NaCl solution      Pb+2 + 2 NaClPbCl2 (s) + 2 Na+

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