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Jonah Chevrier Nick Jiang Ushhud Khalid Philip Van-Lane.

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Presentation on theme: "Jonah Chevrier Nick Jiang Ushhud Khalid Philip Van-Lane."— Presentation transcript:

1 Jonah Chevrier Nick Jiang Ushhud Khalid Philip Van-Lane

2 Introduction  Gravimetric Analysis is used to determine the amount of a substance  Stoichiometry is the study of the relationships between products and reactants  Gravimetric stoichiometry is the combination of gravimetric analysis and stoichiometry

3 Objective  Approximate the amount of Cl - ions in AgCl AgNO 3 (aq) + NaCl (aq)  AgCl (s) + NaNO 3(aq)  Dealing with limiting and excess reagents  Filter out the AgCl from the NaNO 3

4 Materials  Safety Goggles  Distilled Water  NaCl (0.117g) and AgNO 3(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. NaCl solution created 3. Small amounts of AgNO 3 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 Black substances remain; carbon from filter paper which had not totally dissipated NaCl and AgNO3 were clear, aqueous solutions Precipitate of AgCl formed from a double displacement reaction

9 Observations – Qualitative

10 Observations – Quantitative Objects WeighedMass (g) Mass of empty crucible10 Mass of crucible and lid Mass of crucible and NaCl Mass of crucible, NaCl, and lid Mass of NaCl0.117 Mass of crucible and AgCl Mass of AgCl0.3191

11 Calculations n = Number of molecules N A n = _ Mass _ Molar Mass Theoretical: moles Actual: moles Theoretical: * molecules Actual: * 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 NaNO 3(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 17 th and 20 th 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 AgNO 3 (aq) + NaCl (aq)  AgCl (s) + NaNO 3(aq)  g of AgCl * Cl - 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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