Conductimetric Titration and Gravimetric Determination of a Precipitate.docx

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Section 8 ID Number: 2708899 Orlando Lopez Chemistry Lab 266 Dr.Qi 11-28-17 Conductimetric Titration and Gravimetric Determination of a Precipitate Introduction : In an acid-base reaction, disassociation occurs to separate the compounds of both the acid and base into ions until a reaction occurs to where a salt and water are produced. In this experiment, sulfuric acid and barium hydroxide react to produce barium sulfate (a salt precipitate) and water. Due to the compounds abilities to dissociate into ions in solution, they conduct electricity. As sulfuric acid is added to barium hydroxide, the ions react to form the precipitate, meaning less ions exist in solution and the conductivity decreases as a result. Relating the concept of conductivity to ions, the equivalence point can be determined. Using a conductivity probe, when the conductivity value (microsiemens per centimeter) is zero, both reactants are have reached the point of equivalence. Also, after the precipitate develops, the mass of barium sulfate can be determined by evaporating the water out and weighing the salt. Both methods can be used to determine the molar concentration of the unknown barium hydroxide. 1
Materials : Instrumentation: Chemicals: -LabQuest -LabQuest App -Conductor Probe -Disposable Pipet -Drop Counter -Magnetic Stirrer -Micro-stirrer -Stirring Bar -Two Ring Stands -Rind Stand Ring -Utility Clamp -Filter Paper -Balance -Drying Oven -60 mL Reagent reservoir Glassware: -X2 250 mL beakers -50 mL graduated cylinder -10 mL graduated cylinder -filter funnel -100 mL beaker -Barium Hydroxide (Ba(OH) 2 ) -.1 M Sulfuric Acid (H 2 SO 4 ) -Distilled (DI) Water 2 Lopez
Methods: 1.) Lab coat, gloves, and goggles were worn for this lab. 2.) 10 mL of Ba(OH) 2 solution was pipetted into a 250 mL beaker and then 50 mL of DI water was added. 3.) The conductivity probe was configured to the 0-20,000 µS/cm range and connected to the LabQuest. 4.) The plastic 60 mL reagent reservoir was obtained, rinsed with .100 M of H 2 SO 4 , and attached to the ring stand with a utility clamp. 5.) The reagent reservoir was then filled with slightly more than 60 mL of the .100 M of H 2 SO 4 solution.

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