100%(6)6 out of 6 people found this document helpful
This preview shows page 1 - 5 out of 6 pages.
Thermodynamics of Borax DissolutionREBECCA FORLOINELAB PARTNER: DANAMARCH 3, 2015Having read the Georgia Institute of Technology Academic Honor code, I understand and accept my responsibility as a member of the Georgia Tech Community to uphold the Academic Honor Code at all times. In addition, I understand my options for reporting honor violations as detailed in the code.
Data and ResultsA.Data Tables and Plotsa.Table 1. Data for Standardization TrialsMass Na2CO3(g)Volume HCl (ml)[HCl] (mol/L)0.20542.50.09100.27263.00.08100.22051.20.0840Mean [HCl]:0.0853St. Deviation [HCl]:0.00513b.Table 2. Titration of Saturated Borate Solutions with HClTemperate (K)Volume HCl, Endpoint(ml)[borate] (mol/L)29814.00.00059531019.20.0008162869.30.000395c.Table 3. Equilibrium Constants and TemperaturesTemperature (K)Ksp1/T(1/K)ln Ksp2988.43E-100.0034-20.93102.17E-090.0032-20.02862.47E-100.0035-22.1d.Plot 1. Natural Log of Kspversus 1/T
3.15E-033.20E-033.25E-033.30E-033.35E-033.40E-033.45E-033.50E-033.55E-03-22.5-22.0-21.5-21.0-20.5-20.0-19.5-19.0-18.5f(x) = - 6871.43x + 2.15R² = 0.931/Temperature (1/K)ln KspB.Sample Calculationsa.Exact molarity of HCl solution from trial 1i.0.205g N a2C O3×1mol105.99g×10.0425L×2=0.091M HClb.Molarity of borate anion from results of titration (same trial)i.0.0853M HCl ×12=.04265mol Borate ×10.0140L=0.000595M Boratec.Calculations of Ksp (same trial)i.2×0.000595¿2=8.43∗10−100.000595mol×¿d.Calculation of ΔHoi.lnKsp=−Δ HoR(1T)+Δ SoRii.The slope of the graph above is equal to –ΔHo/Riii.Δ Ho=−1(8.314) (−6871.4)=57128J/mole.Calculations of ΔSoi.The y-intercept of plot 1 is equal to ΔSo/Rii.Δ So=(8.314) (2.1471)=17.851J/Kf.Calculations of ΔGoi.ΔG=−RTlnKsp
ii.−8.ΔG=(298K)¿314J/molK)(-20.9) = 51.8kJ/moliii.¿iv.ΔG=Δ H−T ΔSv.ΔG=51.8kJ/molDiscussionA. ObjectivesThe general objectives for this experiment were to measure three chemically important thermodynamic parameters for the dissolution of borax in water. More specifically it was important to quantify borate ion