#6.25 ribbon. In Data Tools, click What-If Analysis and select Goal Seek. In the
ID: 885144 • Letter: #
Question
#6.25 ribbon. In Data Tools, click What-If Analysis and select Goal Seek. In the resulting window, Set cell B4 To value 7.9E-9 By changing cell A4. Click OK and the computer finds -0,00 945 4 in cell A4. Ifyou do not see enough digits in cell A4, drag the separator between columns A and B to the right to expand the cell. To select the number of decimal places displayed, highlight cell A4 and select Number from the Home ribbon. Leaching solution added CI caibration solution added Geladded and BaCi, begins to CI 0.009 6 at end point S-2011 cel -30 r from Ba2 -0 000 19 M before Bacy addition -4.0 End point Using Exco Goal Seek 1Using Excel Goal 0:00 200 4:00 600 800 10:00 12:00 14:00 16.00 Time (h) 41-084 0.0009454 Atter executing Goal Seek Barium sulfate precipitation titration from Phoenix Mars Lander. Before executing Goal Seek (Data from Reference 1, courtesy S. Kounaves, Tufts University. (a) Write the titration reaction. point? How Would You Do Iti -25. Stalfane in sovil on Man. A harium sulfate precipitation titration described at the opening of this chapter is shown in the figure. The initial concentration of CI before adding BaCl, was 0.000 19 M in 25 mL of aqueous extract of Martian soil At the end point, when there is a sudden rise in Ba CT1 0.009 6 M (b) How many mmol of BaCl, were required to reach the end (e)How many mmol of SO? were contained in the 25 ml.? adding Point? n, when there is a sudden rise in Ba". (d)If S04-is derived from 1.0 g of soil, what is the wt% of Sož in the soil? Notes and References 1· S. P Kounaves, M H Hecht, J. Kapit. R. C. Quinn, D. C. Catling, B. C. Clark, D. W. Ming. K. Gospodinova, P. Hredrak, Wiedeman, J. Chem. Ed. 2007, 84, 306. The aquarium K. McElhoney, and J. Shusterman, Geophys, Res. Lett. 2010, 5. H. Van Ryswyk, E. W. Hall, S. J. Petesch, and A. E. K. McElhoney, and J. Shasterman, Geopbys. Res experiment was popularized by Prof. Kenneth Hughes at Georgia Institute of Technology (K. D. Hughes, Anal. Chem 1993, 65, 883A). For other classroom applications of the fishtank, see F. Calascibetta, L. Campanella, and G. Favero, J. Chem. Ed. 2000, 77, 1311 and J. J. Keaffaber, R. Palma, and K. R. Williams, J. Chem. Ed. 2008, 85, 225. 37, L09201 2. W.B. Guenther, J. Chem.Ed 1988, 65, 1097. 3. E. A Buler and E. H. Swift, J. Chem. Ed. 1972, 49, 425. 4 R.W. Ramettc, J. Chem. Ed. 2004, 81, 1715.Explanation / Answer
For a precipitation reaction of BaSO4 starting with the BaCl2 and SO4^2-
(a) Titration reaction is shown as,
SO4^2- + BaCl2 <====> BaSO4 + 2Cl-
(b) As can be seen from the above given chemical equation, 1 mole of SO42- reacts with 1 mole of BaCl2
1 mole of BaCl2 has 2 moles of Cl-
initial mmoles of Cl- = molarity x volume = 0.00019 x 25 = 0.00475 mmol
initial mmoles of BaCl2 = 1/2 x 0.00475 = 0.002375 mmol
Final moles of Cl- at end point = 0.0096 x 25 = 0.24 mmol
mmoles of BaCl2 = 1/2 x mmoles of Cl- = 1/2 x 0.24 = 0.12 mmol
Thus, mmoles of BaCl2 required to reach end point = 0.12 - 0.002375 = 0.11763 mmol
(c) mmoles of SO4^2- in soil = mmole of BaCl2 added to reach the end point
thus, mmole of SO4^2- = 0.11763 mmol
(d) If SO4^2- is derrived from 1.0 g of soil
wt% = mass of SO4^2- x 100/mass of soil
molar mass of SO4^- = 32.06 + 4 x 16 = 96 g/mol
So mass of SO4^2- in soil = mmol x molar mass = 0.11763 x 96 = 11.29248 mg
Thus, wt% of SO4^2- in soil = (0.01129/1) x 100 = 1.13 %
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.