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Unformatted text preview: NAME: titrations: i (a) NaOH with HCI pH (b) BC] with NaOH pH (0) KHP with NaOH pH (d) Na2C03 with HCl pH- l. (16 POINTS) Sketch the shape of the titration curves expected for CHEM 209
- Final Exam
10/2/06 mL HC] mL NaOH mL NaOH mL HC] mw__m.___wqwmmw. the following 2. (24 POINTS) S_uppose a student is determining the total base content of an antacid
tablet by performing a back titration. He/she weighs out a 0.4022~gram portion of a tablet
whose total welght is 1.6665 grams, dissolves this in exactly 30.00mL of deionized I water, and then adds exactly 25.00 mL of 0.1 000M BC] in order to bring the pH down to 2.2. This solution is then carefully back-titrated with 0.1050M NaOH, with 4.77 mL
required to reach the equivalence point. Calculate the total base content (i.e., the number
of moles of base contained) of the antacid tablet. SHOW ALL WORK CLEARLY.
(Formula weight of HG] = 36.46 gram/mole; formula weight of NaOl-I = 40.00 gram/mole). 3. (24 POINTS) (a) Write the equation for Beer’s Law and deﬁne all the terms
(including the correct units for each term). (b) The absorbance of a 1.0 x 10'5M Fe(l ,l 0-phen);2+ solution is measured at a
wavelength of 5] 0 um and found to be 1.00. What is the transmittance of this solution? SHOW YOUR WORK. (0) Suppose the solution in part (b) is diluted with deionized water by a factor of 10.
What are the absorbance and transmittance of the diluted solution? SHOW YOUR WORK. WWWW__-—__—.——.—umumww_.__..__........ .. .. . 4. (16 POINTS) What quantities are plotted on the x— and y-axes of: x-axis -axis (a) a chromatogram? (b) an absomtion spectrum? 5. (8 POINTS) Deﬁne the term “retention time”. What is its principal use in GC
analysis? ' 6. (12 POINTS) Write the equilibrium constant expressions for the following balanced chemical reactions: (a) H3P04 + 3 H20 -———> 1304'3 + 3 1130*
K = (b) Ag2804 (solid) ——+ mg+ + 804'2
K = (c) 2Mn04' + 3 c204” + 4 OH' —————+ 2 MnOz (solid) + 6C032' + 21420 _._._.._._______........m ...
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- Spring '07
- Chemistry, Equivalence point, total base content