Lab 5 - Limiting Reagent Study - Information and Procedure

LAB 5 –LIMITING REAGENT STUDY– INFORMATIONPROCEDURE CHM 2045L -Dr. Yavuz Petrowski HAZARD Cobalt chloride, sodium phosphate and barium chloride may cause irritation to the skin, respiratory tract and eyes. Avoid direct contact. All chemicals are harmful if swallowed or inhaled. SIGNIFICANT FIGURES 10.00mL graduated pipet: The smallest division of this graduated pipet is 0.1mL; therefore, our reading error would be 1/100 of the smallest division. An appropriate reading of this volume would be 4.65mL WASTE COLLECTION PROCEDURE-360 LAB: Part I: Pipettes cleaned thoroughly with water and reagent solutions, for this small amount of the appropriate solution to each pipet is added and r inse d for each solution . The rinse d solution discarded into a waste beaker. Using the information in Table 1, with the pipet, each of the test tubes is filled with the appropriate amount of reactants. Record the exact volume of solutions dispensed into each test tube on your data sheet. Assignment # CoCl2 Na2CO3 Test-tube # 1 2.00 mL 13.00 mL Test-tube # 2 3.00 mL 12.00 mL Test-tube # 3 4.00 mL 11.00 mL Test-tube # 4 6.00 mL 9.00 mL Test-tube # 5 7.50 mL 7.50 mL Test-tube #6 10.00 mL 5.00 mL P arafilm is used to seal the top of the test tube and the test tube is inverted a few times to mix the solutions. Once the reagents have been thoroughly mixed, the solid precipitates is settle d, waited for this about 20 minutes. Once the precipitates in each of the test tubes have settled undisturbed, by using a ruler, the height of solid precipitate is measure d for each test-tube. T he values must be recorded in your lab report . O bservations of the colors of the supernatant liquids and precipitates must be recorded . Part II: Verification of Limiting reagent A 24-well reaction plate is obtained. Using a beral pipet, small amount of the “ supernatant liquid” from the top of test-tube # 1 , and later #2, 3, 4, 5 and 6 is extract ed. Need to be careful not to draw up any precipitate into the dropper A few drops of the liquid from the pipet to wells is added 1 and 2 in the well plate . Test for excess Co 2+ : A few drops of 0.10 M sodium phosphate solution is added to well 1 and observations are made . Test for excess CO 3 2: A few drops of 0.10 M barium chloride is added to well 2 and observations are made . B oth tests for the supernatant liquid of the other test tubes is repeated (test tube: 2, 3, 4, 5, and 6) and observations are recorded. Using the volume and concentration of each starting material, calculate the number of moles of CoCl 2 and Na 2 CO 3 used. Record this value in your data chart. Use the balanced chemical equation : Calculate the # moles of Co 2+ that are present in excess if any. Calculate the # moles CO 3 2that are present in excess if any. Calculate the theoretical yield of the CoCO 3 (moles) from the mole ratio of reactants and products after you have determined which reagent is limiting .