Analytical Chem istry - DePauw University

516 Analytical Chemistry 2.0Some of the problems that follow require one ormore equilibrium constants or standard state potentials.For your convenience, here are hyperlinksto the appendices containing these constantsAppendix 10: Solubility ProductsAppendix 11: Acid Dissociation ConstantsAppendix 12: Metal-Ligand Formation ConstantsAppendix 13: Standard State Reduction Potentials14. A Gran plot method has been described for the quantitative analysisof a mixture consisting of a strong acid and a monoprotic weak acid. 11A 50.00-mL mixture of HCl and CH 3 COOH is transferred to an Erlenmeyerflask and titrated by using a digital pipet to add successive1.00-mL aliquots of 0.09186 M NaOH. The progress of the titrationis monitored by recording the pH after each addition of titrant. Usingthe two papers listed in the footnote as a reference, prepare a Gran plotfor the following data, and determine the concentrations of HCl andCH 3 COOH.Volume ofNaOH (ml) pHVolume ofNaOH (mL) pHVolume ofNaOH (ml) pH1.00 1.83 24.00 4.45 47.00 12.142.00 1.86 25.00 4.53 48.00 12.173.00 1.89 26.00 4.61 49.00 12.204.00 1.92 27.00 4.69 50.00 12.235.00 1.95 28.00 4.76 51.00 12.266.00 1.99 29.00 4.84 52.00 12.287.00 2.03 30.00 4.93 53.00 12.308.00 2.10 31.00 5.02 54.00 12.329.00 2.18 32.00 5.13 55.00 12.3410.00 2.31 33.00 5.23 56.00 12.3611.00 2.51 34.00 5.37 57.00 12.3812.00 2.81 35.00 5.52 58.00 12.3913.00 3.16 36.00 5.75 59.00 12.4014.00 3.36 37.00 6.14 60.00 12.4215.00 3.54 38.00 10.30 61.00 12.4316.00 3.69 39.00 11.31 62.00 12.4417.00 3.81 40.00 11.58 63.00 12.4518.00 3.93 41.00 11.74 64.00 12.4719.00 4.02 42.00 11.85 65.00 12.4820.00 4.14 43.00 11.93 66.00 12.4921.00 4.22 44.00 12.00 67.00 12.5022.00 4.30 45.00 12.05 68.00 12.5123.00 4.38 46.00 12.10 69.00 12.5215. Explain why it is not possible for a sample of water to simultaneouslyhave OH – and HCO 3 – as sources of alkalinity.16. For each of the following, determine the sources of alkalinity (OH – ,HCO 3 – , CO 3 2– ) and their respective concentrations in parts per mil-11 (a) Boiani, J. A. J. Chem. Educ. 1986, 63, 724–726; (b) Castillo, C. A.; Jaramillo, A. J. Chem.Educ. 1989, 66, 341.