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Jonah Chevrier Nick Jiang Ushhud Khalid Philip Van-Lane

Gravimetric Estimation of Chloride Ions. Jonah Chevrier Nick Jiang Ushhud Khalid Philip Van-Lane. Introduction. Gravimetric Analysis is used to determine the amount of a substance Stoichiometry is the study of the relationships between products and reactants

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Jonah Chevrier Nick Jiang Ushhud Khalid Philip Van-Lane

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  1. Gravimetric Estimation of Chloride Ions Jonah Chevrier Nick Jiang Ushhud Khalid Philip Van-Lane

  2. Introduction • Gravimetric Analysis isused to determine the amount of a substance • Stoichiometry is the study of the relationships between products and reactants • Gravimetric stoichiometryis the combination of gravimetric analysis and stoichiometry

  3. Objective • Approximate the amount of Cl- ions in AgCl AgNO3 (aq) + NaCl(aq) AgCl(s) + NaNO3(aq) • Dealing with limiting and excess reagents • Filter out the AgCl from the NaNO3

  4. Materials • Safety Goggles • Distilled Water • NaCl (0.117g) and AgNO3(aq) • Beaker • Erlenmeyer Flask • Dropper • Funnel • 1 piece of (Whatman) filter paper • Porcelain crucible and lid • Crucible tongs • Ring clamp • Retort stand • Clay triangle • Bunsen burner • Accurate scale

  5. Procedure 1. Measured mass of empty crucible 2. NaClsolution created 3. Small amounts of AgNO3 added 4. AgCl filtered using filter paper and funnel

  6. Procedure Part 2 5. After the filter paper had dried, it was carefully placed in the crucible 6. Filter was allowed to burn; AgCl remained in the crucible 7. Found mass of AgCl

  7. Safety Precautions • Safety goggles were worn at all times • Workspace was free of clutter • All hot materials were handled with care • All substances were handled properly

  8. Observations – Qualitative • NaCl and AgNO3 were clear, aqueous solutions • Precipitate of AgCl formed from a double displacement reaction • Black substances remain; carbon from filter paper which had not totally dissipated

  9. Observations – Qualitative

  10. Observations – Quantitative

  11. Calculations n = Number of molecules NA • n = _ Mass _ • Molar Mass Theoretical: 0.002 moles Actual: 0.002226475 moles Theoretical: 1.2044 * 1021 molecules Actual: 1.3407843432 * 1021 molecules

  12. Calculations Part 2 Percentage Yield | Actual / Theoretical | *100 =111.32% Percentage of Error | (Theoretical – Actual) / Theoretical | *100 =11.32%

  13. Discussion • Initial problem was to separate AgCl(s) from the NaNO3(aq) • Both have very high boiling points; evaporation would not be feasible • Gravimetric analysis was used for convenience

  14. Discussion Part 2: Analytical Chemistry • Study of chemical composition of natural and artificial materials • Deals with 3 main questions • What chemicals are present? • Characteristics of the chemicals? • Quantity of the chemicals? • Quantitative • Amount of chemicals • Qualititative • Determining presence of chemicals

  15. Analytical Chemistry Part 2 • Much focus on it between the 17th and 20th centuries • First kind of instrumental analysis flame emissive spectrometry • Robert Bunsen, 1860 • Most studied branch of chemistry

  16. Discussion Part 3: Thermogravimetric Analysis • Part of instrumental analysis branch • Study of weight changes in relation to temperature • Used to determine characteristics of polymers • Large molecules composed of repeating structural units

  17. Discussion Part 4: Volumetric Titration • Another traditional analytical technique • Reagent of known concentration and volume • Titrant • Solution of unknown volume and concentration • Titrand

  18. Volumetric Titration Part 2 • Volume, instead of mass, is measured • Titrant is added to titrand until endpoint is reached • Indicators make endpoint obvious to observers • Most often used for neutralization reactions • Acid + Base  Water + Ionic Salt

  19. Conclusion • Precipitate of AgCl formed through double displacement reaction AgNO3 (aq) + NaCl(aq) AgCl(s)+ NaNO3(aq) • 0.3191g of AgCl • 1.3407843432 * 1021Cl- ions in precipitate • Carbon particles remained • Added to mass

  20. Sources of Error • Inconsistence balance readings • Contamination of chemical substances • Uncertain if the Cl- ions had completely reacted with the Ag+ ions • Qualitative filter paper did not disintegrate • Residue left in crucible from previous experiments

  21. Suggested Modifications • Use of quantitative filter paper rather than qualitative • More accurate balances • Using materials which may not have been contaminated from previous experiments

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