课程名称︰分析化学 课程性质︰必修 课程教师︰林金全 开课学院：化学系 开课系所︰理学院 考试日期（年月日）︰05-05-08 考试时限（分钟）：两小时 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : 1. Consider the peaks for n-C7H16 and 1,4-diflurobenzene in the chromatogram show below. The elution time for unretained solute is 1.06 min. The open tubular column is 30.0 m in length and 0.530 min in diameter, with a layer of stationary phaes 3.0 μm thick on the inner wall. a). Find the adjusted retention times and capacity factors foe both compounds. b). Find the relative retention, α. c). Find the seperation factor, γ. d). Measuring W(1/2) on the chromatogram, find the number of plates, N1 and N2, and the plate height for these two compounds. e). Measuring the width, w, at the baseline on the chromatogram, find the number of plates for these two compounds. f). Use your answer to part (e) to find the resolution between the two peaks. g). Using the number of plates [N]=√N1N2 , with values from part (e) and the observed seperation factor, caculate what the resolution should be and compare your answer with the measured resolution in part (f). 14% 2. Suppose that the acid HA (with dissociation constant Ka ) is partitioned between aqueous phase 1 and organic phase 2. Calling the partition coefficient K for HA and assuming that A- is not soluble in hte organic phase. (a). show that ths distribution coefficient is given by: K。[H+] D= －－－－ = K。αHA [H+] + Ka (b). If K = 3.0 for an amine (B) and Ka = 1.0x10^-9 for the BH+, and if 50 ml of 0.010M aqueous amine is extracted with 100 mL of solvent, what will be the formal concentration remaining in the aqueous phase at pH 9.00? 16% 3. An electrospray/trasmission quadrupole mass spectrum of the α chain of hemoglobin feom acidic solution exhibits nine molecular mass of the neutral protein, M, from peak A,B,G,H, and I, and find the mean value. 14% Peak mlz Amplitude Peak mlz Amplitude A 1261.5 0.024 F not satated 1.000 B 1164.6 0.209 G 834.3 0.959 C not stated 0.528 H 797.1 0.546 D not stated 0.922 I 757.2 0.189 E not stated 0.959 4. Find the number of rings plus double bonds in molecules with the f following composition and draw one plausible strcture for each (a) C11H18N2O3 (b) C12H15BrNPOS；(c) a fragment in a mass spetrum with the composition C3H5+ 12% 5. The first excited state of Ca ia reached by absorption of 422.7nm light. (a). Find the energy difference(kJ/mol) between ground and excited states. (b). The degeneracies are g*/g0 =3 for Ca. Find N*/N0 at 2500 K. (c). By what percentage will N*/N0 change with a 15 K rise in temperature? (d). Find N*/N0 at 6000 K. 16% 6. The laser atomic fluorescence excitation and emission spectrum os sodium are in an air acetylene flame. In the excitation spectrum, the laser (bandwidth = 0.03 nm) was scanned through various wavelengths while the detector monochromator (bandwidth = 1.6 nm ) was held fixed near 589.0 nm. In the emission spectrum, the laser was fixed at 589.0 nm. monochromator wavelength was varied. Explain why the emission spectrum given one board band, whereas the excitation spectrum given two sharp lines. How can the excitation linewidths ba much narrower than detector monochromator bandwidth? 12% 7.(a) How do the timeof flight mass spectrometer and ion mobility spectrometer seperate the positive ions? (b) Explain the method of D2 lamp background correction used in graphite furnance atomic absoprtion measurments. (c) Explain operation of inductively- coupled plasma(ICP) torch. (d) Briefly describe two method for introducing eluate from liquid chromatography into a mass spectrometer. 20% --

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