Topic 4 Block A

1. Group 4: SolubilityBlock ACarolina ZarateJason WangMichael Yeh

2. TitleIntroduction The Problem Basic Research Balanced Equation Previous Experiments Why? HypothesisStella Model The Solvation Process Deriving the Equation The Dynamic Model Evaluating the ModelProcedure Materials MethodsData Analysis Data PHS Block A Boxplots Overall Boxplots Graph ComparisonAnalysisProblems Encountered ConclusionSourcesIntroduction

3. IntroductionThe ProblemGeneral Question:What is the effect of temperature on solubility of salts?Tested Question:What is the effect of temperature on the solubility of potassium nitrate at temperatures of 0oC, 25oC, and 60oC?

4. IntroductionBasic ResearchBasic facts about Potassium nitrate, or KNO3Potassium nitrate canbe dissolved in waterIt is an orthorhombic crystal.Its melting pointis 334oCIts boiling pointis 400oC

5. IntroductionBalanced EquationThe equation for our experiment:KNO3(s) + H2O(l) ->K+(aq) + NO3-(aq) + H2O(l)The net ionic equation simplifies to:KNO3 (s) ->K+ (aq) + NO3- (aq)

6. IntroductionPrevious ExperimentsOur research found sources created by other scientists working in this field:Empirical data found in other researchers’ previous experimentsThe data showed an exponential increase in solubility with temperature

7. IntroductionWhy?Real-world applications of the results gathered from our experiment include:Solutions in cooking and food

8. Solutions found in living organisms

9. Industry, such as ore processingIntroduction HypothesisThe solubility of potassium nitrate is expected to increase exponentially as temperature increases.Other solids soluble in water follow similar trends

10. A dynamic model in was created in Stella and used to predict the solubility at each temperatureTitleIntroduction The Problem Basic Research Balanced Equation Previous Experiments Why? HypothesisStella Model The Solvation Process Deriving the Equation The Dynamic Model Evaluating the ModelProcedure Materials MethodsData Analysis Data PHS Block A Boxplots Overall Boxplots Graph ComparisonAnalysisProblems Encountered ConclusionSourcesStella Model

11. Stella ModelThe Solvation ProcessWhen KNO3 and H2O form a solution, the KNO3 dissociates into K+ and NO3- ions.

12. At equilibrium, a pair of ions will recombine for each pair that disassociates

13. The solubility product constant for our solution isKsp= [K+][NO3-]NO3-NO3-NO3-NO3-NO3-NO3-K+K+K+K+K+K+Dissolving potassium nitrate

14. Stella ModelDeriving the EquationGibbs-Helmholtz Equation: G = H - T * SRelationship between Ksp and G:G = -R * T * ln(Ksp)H - T * S = -R * T * ln(Ksp)ln(Ksp) = (H - T * S) / (-R * T)Ksp = e(S / R -H / (R * T))H: Enthalpy changeS: Entropy changeG: Free energy changeT: Temperature (Kelvin)R = 8.314 J/(mol*K)

15. Stella ModelDeriving the EquationKsp= [K+][NO3-] = x2x2 = eS / R - H / (R * T)x = Sqrt(eS / R - H / (R * T))ICE box: x is the solubility

16. Stella ModelThe Dynamic ModelThe values for S and H were found in The CRC Handbook of Physics and Chemistry

17. Stella ModelThe Dynamic ModelPredictions:0°C:13 g KNO3per 100 mL H2O.25°C: 37.5 g KNO3 per 100 mL H2O.60°C: 71.73 g KNO3 per 100 mL H2O.

18. Stella ModelEvaluating the ModelReasons for the linear solubility curve:Only one changing variable, T

19. More accurate at lower temperatures

20. To fix this, it would have been necessary to find the change in temperatureTitleIntroduction The Problem Basic Research Balanced Equation Previous Experiments Why? HypothesisStella Model The Solvation Process Deriving the Equation The Dynamic Model Evaluating the ModelProcedure Materials MethodsData Analysis Data PHS Block A Boxplots Overall Boxplots Graph ComparisonAnalysis Problems Encountered ConclusionSourcesProcedure

21. ProcedureMaterials1 PASCO Explorer GLX (#4)1 GLX Temp Probe (Stainless Steel Chemical Resistant)20 Weighing Boats1 Analytical Scale1 Glass Funnel1 1000 mL Beaker1 10 mL Graduated Cylinder1 Vacuum Flask4 50 mL Erlenmeyer Flasks1 Hot Plate1 Mixer (Separate from hot plate)10 mL Tap Water (H2O) per Trial6 g KNO3 per TrialIce: enough to fill a 1000 mL Beaker1 Plastic Pipette15 Filter Papers1 Small Magnetic Stirrer Pill1 Magnet to take out the Pill

22. ProcedureMethodsMeasure 10 mL of tap water and pour into Erlenmeyer flask.Put Erlenmeyer flask onto a hot plate and heat to 60oC. (Use GLX to measure temperature)

23. ProcedureMethodsMeasure 6 g of potassium nitrate in a weighing boat on an analytical scaleRemove the Erlenmeyer flask from the hot platePour the potassium nitrate and the magnetic stirrer into the Erlenmeyer flask

24. ProcedureMethodsPay attention to the temperature as the KNO3 dissolves.Allow the magnetic stirrer to run for 2-5 minutesRemove the magnetic stirrer and temperature probe

25. ProcedureMethodsPlace a filter paper into the funnel, and insert into the vacuum flaskPour the contents of the Erlenmeyer flask through the filter paperRemove the filter paper and place on the table to dry.

26. ProcedureMethodsPlace an unused filter paper on the analytical scale and zero itPlace the dry paper with the potassium nitrate on the scale to weigh the undissolved soluteSubtract the weight from 6 g

27. ProcedureMethodsRepeat this process 4 more timesRepeat 1-15, but heat water to 25oC insteadRepeat 1-15, but use an ice bath to cool water to 0oCDrying KNO3Ice Bath

28. TitleIntroduction The Problem Basic Research Balanced Equation Previous Experiments Why? HypothesisStella Model The Solvation Process Deriving the Equation The Dynamic Model Evaluating the ModelProcedure Materials MethodsData Analysis Data PHS Block A BoxplotsOverall Boxplots Graph ComparisonAnalysis Problems Encountered ConclusionSourcesData & Analysis

29. Data & AnalysisDataWe did 15 trials, 5 trials at each temperature

30. We used 10 mL of water and 6 g of KNO3 per trial, but we scaled our results up to 100 mL and 60 gData & AnalysisData

31. Data & AnalysisPHS Block A Boxplots0°CMedian: 15.8Minimum: 13.8Maximum: 19.4Interquartile Range: 3.2525°CMedian: 23.1Minimum: 22.5Maximum: 23.5Interquartile Range: 0.860°CMedian: 41.2Minimum: 38.1Maximum: 43.3Interquartile Range: 3.75

32. Data & AnalysisOverall Boxplots0°CMedian: 13.3Minimum: 2.40Maximum: 25.20Interquartile Range: 3.8375Outliers: 2.40 5.25 5.40 6.64 25.20 19.425°CMedian: 33.50Minimum: 13.23Maximum: 45.20Interquartile Range: 11.8Outlier: 13.2360°CMedian: 74.75Minimum: 24.72Maximum: 123.00Interquartile Range: 63.92Outliers: none

33. Data & AnalysisGraph ComparisonOur data graph intersects overall data graph

34. Large difference in 60°C dataData & AnalysisAnalysisOur low IQRs mean the data is very precise

35. Mean and median are fairly close, meaning data is consistent

36. Data did increase exponentially, but not exactly as predicted

37. 0oC trials dissolved more than expected; room temperature heated the solution

38. 60oC dissolved less than expected; room temperature cooled the solutionData & AnalysisAnalysisOverall results closely match results from professional experiments

39. Lots of inconsistencies shown in the boxplots

40. Much larger IQR for 60oC than our block alone

41. More outliers for 0oC: 6 as opposed to 1 and none

42. Variations in data due to different procedures

43. Even with larger IQRs and more outliers, mean and medians of the 155 trials match our hypothesis closelyData & AnalysisProblems EncounteredMaintaining temperature: cooling to 0o and heating to 60oC

44. Rate of dissolution: used a magnetic stirrer to accelerate process

45. Transferring solution: wet residue stuck to sides of flask, used spatula to remove it

46. Measuring remnants: wet filter paper was inconsistent, waited for the crystals to dryData & AnalysisConclusionHypothesis confirmed: the solubility did increase exponentially when the temperature increased.155 trials not enough to definitively answer the question – it does provide solid evidence

47. In the future, more data can be collected using same methods

48. Possible variations:

49. Change temperatures tested

50. Use different salts instead of KNO3SourcesAustin Peay State University. (n.d.). Introduction. In Solubility and Thermodynamics of Potassium Nitrate. Retrieved from Department of Chemistry, Austin Peay State University website: http://www.apsu.edu/‌files/‌chemistry/‌Solubility_and_Thermodynamics_of_Potassium_Nitrate_RF9.pdfBender, H., & Francis, E. (2003). Dissolution Reactions. Retrieved April 5, 2011, from Clackamas Community College website: http://dl.clackamas.edu/‌ch105-03/‌dissolut.htmButhelezi, T., Dingrando, L., Hainen, N., Wistrom, C., & Zike, D. (2008). Chemistry: Matter and Change. Columbus, OH: Glencoe/‌McGraw-Hill.Clark, J. (2005). Solubility Curves. In Solid-Liquid Phase Diagrams: Salt Solution. Retrieved from http://www.chemguide.co.uk/‌physical/‌phaseeqia/‌saltsoln.htmlDebelius, B. B., Gómez-Parra, A., & Forja, J. (2009). Oxygen solubility in evaporated seawater as a function of temperature and salinity. Retrieved from EBSCOhost database. (43264914)Determination of Saturation Temperature Method. (n.d.). Solubility of Salts. Retrieved April 5, 2011, from College of DuPage website: http://www.cod.edu/‌dept/‌chem/‌poc/‌Experiments/‌PotassiumNitrate-02/‌Solubility.htm#IntroGrow, J. M. (1999, August). Heat of Solution. Retrieved April 5, 2011, from New Jersey Institute of Technology website: http://www-ec.njit.edu/‌~grow/‌Heatsolution/‌HeatofSolution.htmlLerner, E. K. L., & Lerner, B. W. (2008). Solubility. Retrieved April 5, 2011, from Gale Science in Context database. (CV2644032069 )Lide, D. R. (Ed.). (2003-2004). CRC Handbook of Chemistry and Physics [PDF] (84th ed.).Mierdel, K., & Keppler, H. (2004, August 5). Abstract. In The Temperature Dependence of Water Solubility in Enstatite. Retrieved from EBSCOhost database. (14964762)Newton, D. E. (1999). Chemical Elements: From Carbon to Krypton: Vol. 3. P-Z (L. W. Baker, Ed.). Farmington Hills, MI: UXL.Silberman, R. G. (1999). The Thermodynamics of Potassium Nitrate Dissolving in Water (H. D. Schreiber, Ed.) [Pamphlet]. Retrieved from http://cerlabs.brookscole.com/‌experiments/‌10875405126.pdfSolubility Product Constants, Ksp. (n.d.). Retrieved April 20, 2011, from Purdue University website: http://www.chem.purdue.edu/‌gchelp/‌howtosolveit/‌equilibrium/‌solubility_products.htm#SolubilitypureSTELLA Models . (n.d.). Retrieved April 20, 2011, from Williamsport High School website: http://www.wcboe.k12.md.us/‌custom_pages/‌430/‌main_old/‌mvhs/‌stella/‌index.htmlUniversity of Virgina Physics Department. (2009). Temperature Effect on Solubility. Retrieved March 5, 2011, from University of Virginia website: http://galileo.phys.virginia.edu/‌education/‌outreach/‌8thgradesol/‌TempSolubility.htmZumdahl, S. S. (1989). Chemistry (2nd ed.). Lexington, Massachusetts: D.C. Heath and Company. doi:10.1021/‌ed066pA231.1

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