jonah chevrier nick jiang ushhud khalid philip van-lane
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
Jonah ChevrierNick Jiang
Ushhud KhalidPhilip Van-Lane
Gravimetric Estimation of Chloride Ions
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
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
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
Procedure1. Measured mass
of empty crucible
2. NaCl solution created
3. Small amounts of AgNO3 added
4. AgCl filtered using filter paper and funnel
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
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
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
Observations – Qualitative
Observations – Quantitative
Objects Weighed Mass (g)Mass of empty crucible 10Mass of crucible and lid 15.871
Mass of crucible and NaCl 10.117Mass of crucible, NaCl, and lid 15.988
Mass of NaCl 0.117Mass of crucible and AgCl 10.3191
Mass of AgCl 0.3191
Calculations
n = Number of moleculesNA
n = _ Mass _ Molar Mass
Theoretical: 0.002 molesActual: 0.002226475 moles
Theoretical: 1.2044 * 1021 moleculesActual: 1.3407843432 * 1021 molecules
Calculations Part 2
Percentage Yield | Actual / Theoretical | *100
=111.32%
Percentage of Error| (Theoretical – Actual) / Theoretical |
*100=11.32%
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
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?
QuantitativeAmount of chemicals
QualititativeDetermining presence of chemicals
Analytical Chemistry Part 2
Much focus on it between the 17th and 20th centuries
First kind of instrumental analysis flame emissive spectrometryRobert Bunsen, 1860
Most studied branch of chemistry
Discussion Part 3: Thermogravimetric Analysis
Part of instrumental analysis branch
Study of weight changes in relation to temperature
Used to determine characteristics of polymersLarge molecules composed of
repeating structural units
Discussion Part 4: Volumetric Titration
Another traditional analytical technique
Reagent of known concentration and volumeTitrant
Solution of unknown volume and concentrationTitrand
Volumetric Titration Part 2
Volume, instead of mass, is measured
Titrant is added to titrand until endpoint is reachedIndicators make endpoint obvious to
observers Most often used for neutralization
reactionsAcid + Base Water + Ionic Salt
Conclusion Precipitate of AgCl formed through double
displacement reaction
AgNO3 (aq) + NaCl(aq) AgCl(s) + NaNO3(aq)
0.3191g of AgCl1.3407843432 * 1021 Cl- ions in precipitate
Carbon particles remained Added to mass
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
Suggested Modifications Use of quantitative filter paper
rather than qualitative More accurate balances Using materials which may not
have been contaminated from previous experiments