“Known” CompoundsTestsSubstances in 1st GroupSubstances in 2nd GroupConductivityBial’s ReagentGroupGroup CharacteristicsSubstances IncludedRevised 1/08, AJGIntroductory Lab PracticalOBJECTIVES:This exercise introduces the general skills and strategies you must learn in lab this semester to successfully complete the final lab practical. These skills include: finding regularities in observed data, construction of a flow chart, and analysis of an “unknown”. Furthermore, this lab is designed to teach you how to prepare solutions and take measurements using the Vernier equipment. ASSIGNMENT:You will establish the identity of an unknown sample. Your task is divided into the following parts:1. Perform a series of preliminary tests on six known compounds.2. Examine observed data for similarities and arrange compounds in groups.3. Develop a “Flow Chart”.4. Devise a strategy based on the results to establish the identity of an unknown.5. Test your strategy.The unknown you must identify will be one of the six known compounds studied:NaOH Ba(OH)2 NaCl BaCl2ribose waterPROCEDURE:For the following tests, you must start with an aqueous solution of the compound. A solution is one substance dissolved in another. Therefore, if the standard is provided as a solid, you should dissolve it in a small amount of water before performing the tests. If the sample contains a liquid, it was already dissolved for you and Step 1 is not needed.1. In separate test tubes for each sample, place a pea sized amount of sample and add approximately 10 mL of water and stir until dissolved. You should stir for a few minutes in case the dissolving process is slow. If the solid does not completely dissolve, add a few more drops of water and stir again. 2. Test the pH of each sample using pH paper. Record the pH in your data table, and then “generalize” using the following guide: “Low” = < 3, “Medium” = 4 – 9, and “High” = >10. 3. Test and record the conductivity of each sample using the conductivity probe. The probe should be set on the highest range (0-20,000). Once again, generalize the measurements using “Low”, “Medium”, and “High” as descriptors of the conductivity.Introductory Practical - 14. In separate test tubes; obtain 1 mL of “Bial’s Reagent” for each of the six aqueous samples. Add 5 drops of sample to the reagent and heat the mixture using a boiling water bath for 1-2 minutes. Record your observations in your data table. If there is no observablechange, it should be recorded as “NR” for “No Reaction”. 5. Add 3 drops of 1 M Na2SO4 to each sample and record your observations. Again, if no observable change occurs, record “NR”.DATA: (Preliminary Tests)“Known” CompoundsTests Water Ribose NaCl BaCl2NaOH Ba(OH)2pHPaperConductivityBial’sReagentNa2SO4Reagent DATA ANALYSIS:Finding Regularities:1. Examine your data table. Individual tests should allow you to divide the six substances into two groups. The substances in each group will vary depending on the test. Using yourdata, determine the substances in the two groups for each test. Test Substances in 1st Group Substances in 2nd GrouppHConductivityBial’s ReagentNa2SO4 ReagentIntroductory Practical - 22. Examine your data again. Using the combined results of two tests, it is possible to divide the substances into three groups of two. Identify the two tests that would do this, give thecharacteristics of each group, and identify the substances in each group. Tests Group Group Characteristics Substances Included1st Group2nd Group3rd GroupDeveloping a Flow Chart: 3. A flow chart (sequence of steps) is a convenient tool when developing a plan to separate and identify substances. Use the space below to develop a flow chart to identify the six substances in this lab.Introductory Practical - 3Report Sheet for Introductory PracticalNAME: Section: Date: Obtain an unknown from your instructor. Record the unknown number. Perform appropriate tests to determine the identity of your unknown.Identification: Unknown # ___________ is ________________. Reasoning: In the space below, describe in detail how you reached your conclusions.Introductory Practical - 4Bial's Reagent: Dissolve 3 g orcinol in 500 mL concentrated HCl, add 2.5 mL of a 10% solution of ferric chloride hexahydrate, and dilute to one liter with water; this is approximately 6 M HCl. The reagent is stable for months, but its yellow color gradually darkens and some precipitate forms; this doesn't seem to affect its reactivity. The "classical" Bial's reagent is made with a liter of concentrated HCl, undiluted with water. It gives a slightly stronger reaction, and considerably faster (30-60 seconds), but is much less stable than the recipe we've come up with, and the fumes are much more a problem with concentrated than with 6 M HCl. The reaction even seems to work, more slowly and with less intense color, if the final HCl concentration is only 4 M. When 1 mL of reagent is heated with 5 drops of sample in a boiling water bath, a positive test for pentoses is formation of a green to blue color (not precipitate) in less than five minutes.Introductory Practical -