Experiment 1: Calorimetry

Experiment 1: Calorimetry Nadya Patrica E. Sauza, Jelica D. Estacio Institute of Chemistry, University of the Philippines, Diliman, Quezon City 1101 Philippines Results and Discussion Eight Styrofoam globe calorimeters were calibrated. Five milliliters of 1M hydrochloric acute (HCl) was reacted behind a suitableness 10 ml of 1M sodium hydroxide (NaOH) in each calorimeter. The weather anteriorly and behind the reaction were chronicled; the veer in weather (? T) was congenial by subtracting the judicious weather from the decisive weather. The reaction was done twice for perfect calorimeter. The ebullition space (Ccal) of each calorimeter was congenial using the formula, C_cal=(-?? H? _rxn^o n_LR)/? T[1] where ? Horxn is the undiminished ebullition attentive or evolved for perfect deference of reaction and nLR is the reckon of deferences of the limiting reactant. The ? Horxn used was -55. 8kJ per deference of insinuate suitableness the nLR was 0. 005 deference. Consultation 1. Average Ccal from chronicled ? T values. Trial? T, (oC)Ccal, (J)Ave Ccal, (J) 112. 2126. 82202. 91 21. 0279. 00 213. 093. 00108. 50 22. 3124. 00 310. 5558. 00558. 00 20. 5558. 00 412. 0139. 50244. 13 20. 8348. 75 513. 093. 0081. 38 24. 069. 75 612. 0139. 50209. 25 21. 0279. 00 712. 111. 60111. 60 22. 5111. 60 813. 093. 00116. 25 22. 0139. 50 Irrelative ebullition capacities were congenial for each calorimeter (Table 1). Behind calibration, a reaction was done in a calorimeter by each brace. A undiminished of eight reactions were observed by the undiminished collocate. The weather anteriorly and behind the reaction were chronicled. Then the veer in weather was congenial. Each reaction was done twice to consequence two trials. The tentative ? Horxn for each reaction was work-outd using the formula, ?? H? _rxn^o=(-C_cal ? T)/n_LR [2] where Ccal is the ebullition space previously congenial for each calorimeter. The percent blunder for each reaction was computed by comparing the computed tentative ? Horxn to the presumptive ? Horxn using the formula, % blunder=|(computed-theoretical)/theoretical|? 100% [3] Consultation 2. Comparison of congenial ? Horxn and presumptive ? Horxn. RxnLRTrial? T, (oC)? Horxn, (kJ/mol)Ave ? Horxn, (kJ/mol)Theo ? Horxn, (kJ/mol)% Blunder 1HCl13. 5-142. 04-131. 89-132. 510. 47 23. 0-121. 75 2HOAc11. 3-26. 34-41. 61-56. 0924. 65 22. 7-56. 89 3HOAc11. 8-189. 61-203. 16-52. 47287. 18 22. 0-216. 70 4HNO311. 5-73. 24-70. 80-55. 8426. 78 21. 4-68. 36 5Mg13. 0-118. 67-138. 45-466. 8570. 34 24. 0-158. 23 6Mg15. 5-559. 4-635. 72-953. 1133. 30 27. 0-712. 01 7Zn13. 0-43. 80-43. 80-218. 6679. 97 23. 0-43. 80 8CaCl210. 00. 00-5. 8113. 07144. 47 20. 5-11. 63 There were unlikenesss in tentative and presumptive values of ? Horxn as shown by the percent blunder for each reaction (consultation 2). The discrepancies were caused by frequent elements. One element was the forfeiture of ebullition. The ebullition may feel been loosed when the thermometer was pushed or pulled during the reaction. The ebullition may as-well feel been obsolete owing the calorimeter is not undiminishedly unaffected. Another element was the inconclusiveness of the resolution. The pipette or standard tube may tranquil feel been wet when used. However, the ardor used in solving for values was the ardor of the unmalleable resolution. Another element that may feel addd to the unlikeness in the tentative and presumptive values was rational blunder. It was manifested when lection the thermometer or measuring chemicals behind a suitableness irrelative instruments. The elements aforementioned are the limitations of this experience. References Petrucci, R. H. ; Herring, F. G. ; Madura, J. D. ; Bissonnette, C. General Chemistry, 10th ed. ; Pearson Education: Canada, 2011; Chapter 7. Appendices Appendix A Comparison of Observed and Presumptive Heats of Reactions RxnLRTrial? TnLRqrxn? HorxnAve ? HorxnTheo ? Horxn% Blunder 1HCl13. 500. 00500-710. 19-142. 04-131. 89-132. 510. 47 23. 000. 00500-608. 73-121. 75 2HOAc11. 250. 00515-135. 63-26. 34-41. 61-56. 0924. 65 22. 700. 00515-292. 95-56. 89 3HOAc11. 750. 00515-976. 50-189. 61-203. 16-52. 47287. 18 22. 000. 00515-1116. 00-216. 70 4HNO311. 500. 00500-366. 19-73. 24-70. 80-55. 8426. 78 21. 400. 00500-341. 78-68. 36 5Mg13. 000. 00206-244. 13-118. 67-138. 45-466. 8570. 34 24. 000. 00206-325. 50-158. 23 6Mg15. 500. 00206-1150. 88-559. 44-635. 72-953. 1133. 30 27. 000. 00206-1464. 75-712. 01 7Zn13. 000. 00764-334. 80-43. 80-43. 80-218. 6679. 97 23. 000. 00764-334. 80-43. 0 8Na2CO3/ CaCl210. 000. 005000. 000. 00-5. 8113. 07144. 47 20. 500. 00500-58. 13-11. 63 Appendix B Sample Calculations Calibration of Calorimeter 10ml 1M NaOH + 5ml 1M HCl n. i. e. : OH-(aq) + H+(aq) ? H2O(l)? Horxn= -55. 8kJ LR: HCLnLR= 0. 005mol Grp 1 Trial 1 ?T= 2. 2oC Sol’n: C_cal=(-?? H? _rxn^o n_LR)/? T C_cal=(-(-55. 8kJ)(0. 005mol))/(? 2. 2? ^o C)? 1000J/1kJ ?(C_cal=126. 82 J) Determination of Heats of Reaction Neutralization Reaction Rxn 4 Trial 1: 10ml 1M NaOH + 5ml 1M HNO3 n. i. e. : OH-(aq) + H+(aq) ? H2O(l) LR: HNO3nLR= 0. 005mol ?T= 1. 5oCCcal= 244. 125 J Sol’n ?? H? _rxn^o=(-C_cal ? T)/n_LR ?? H? _rxn^o=(-(244. 25J)(? 1. 5? ^o C))/0. 005mol? 1kJ/1000J ? (?? H? _rxn^o=-73. 24kJ) Reaction among an Active Metal and an Acute Rxn 5 Trial 1: 15ml 1M HCl+ 0. 05g Mg n. i. e. : 2H+(aq) + Mg(s) ? Mg+2(aq) + H2(g) LR: MgnLR= 0. 00206mol ?T= 3oCCcal= 81. 375 J Sol’n ?? H? _rxn^o=(-C_cal ? T)/n_LR ?? H? _rxn^o=(-(81. 375J)(3^o C))/0. 00206mol? 1kJ/1000J ?(?? H? _rxn^o=-118. 67kJ) Displacement of One Metal by Another Rxn 7 Trial 1: 15ml 1M CuSO4 + 0. 5g Zn n. i. e. : Cu+2(aq) + Zn(s) ? Zn+2(aq) + Cu(s) LR: ZnnLR= 0. 00764mol ?T= 3oCCcal= 111. 6 J Sol’n ?? H? _rxn^o=(-C_cal ? T)/n_LR ?? H? _rxn^o=(-(111. 6J)(3^o C))/0. 00764mol? 1kJ/1000J ?(?? H? rxn^o=-43. 80kJ) Precipitation Reaction Rxn 8 Trial 1: 10ml 0. 5M Na2CO3 + 5ml 1M CaCl2 n. i. e. : CO3-2(aq) + Ca+2(aq) ? CaCO3(s) LR: Na2CO3/ CaCl2nLR= 0. 005mol ?T= 0. 5oCCcal= 116. 25 J Sol’n ?? H? _rxn^o=(-C_cal ? T)/n_LR ?? H? _rxn^o=(-(116. 25J)(? 0. 5? ^o C))/0. 005mol? 1kJ/1000J ? (?? H? _rxn^o=-11. 63kJ) Appendix C Answers to the Questions in the Lab Manual There are frequent possibilities that elucidate the dissonance of the tentative and presumptive values of ? Horxn. First, ebullition susceptibility feel been obsolete to the verbiage. This is practicable whenever the thermometer is pulled out or pushed in the calorimeter during the reaction. Also, the calorimeter susceptibility not feel been thoroughly unaffected. Second, the rerediscontinuance susceptibility feel been malleable in the standard tube or pipette. They susceptibility feel been wet when used behind a suitableness the resolution. Lastly, the discrepancies susceptibility feel occurred due to rational blunder. The students susceptibility feel misobserve the thermometer when presentation the weather or the pipette when measuring the resolutions. a. It is relevant to celebrate the undiminished faculty of the resulting rerediscontinuance to 15ml owing any further or any close than that of the faculty can add to the aridity or loose of additional ebullition accordingly considerable the ? Horxn. b. It is relevant to understand the correct ardors of the reactants to work-out for their reckon of deferences and to experience out the limiting reactant. c. It is relevant to understand the correct burden of the metal denses used to work-out for their reckon of deferences and to experience out whether one of them is a limiting reactant. Also, the burden is needed to work-out for the ebullition space of the dense when the particular ebullition is loving. 200ml 0. 5M HA + NaOH ? -6. 0kJ LR: HAnLR= 0. 1deference ?? H? _(rxn,mol)^o= (-6. 0 kJ)/(0. 1 mol) ?(?? H? _(rxn,mol)^o= -60 kJ) HA is a stanch acute. OH-(aq) + H+(aq) ? H2O(l)? Horxn= -60 kJ/deference Calibration:15ml 2. M HCl + 5ml 2. 0M NaOH? T=5. 60oC LR: NaOHnLR= 0. 01deference Reaction:20ml 0. 450M CuSO4 + 0. 264g Zn? T=8. 83oC LR: ZnnLR= 0. 00404deference n. i. e. : OH-(aq) + H+(aq) ? H2O(l) n. i. e. : Cu+2(aq) + Zn(s) ? Zn+2(aq) + Cu(s) C_cal=(-?? H? _rxn^o n_LR)/? T C_cal=(-(-55. 8kJ)(0. 01mol))/(? 5. 60? ^o C)? 1000J/1kJ ?(C_cal=99. 6 J) ?? H? _rxn^o=(-C_cal ? T)/n_LR ?? H? _rxn^o=(-(99. 6J)(? 8. 83? ^o C))/0. 00404mol? 1kJ/1000J ? (?? H? _rxn^o=-218. 0 kJ) OH-(aq) + H+(aq) ? H2O(l)? Horxn= -55. 8kJ ?Hof,H2O= -285 kJ ?Hof,OH-= ? ?Horxn= ? Hof,consequence - ? Hof,reactant -55. 8 kJ = ? Hof,OH- - (-285 kJ) ?(?? H? _(f,? OH? ^-)^o=-218. 0 kJ)