課程名稱︰分析化學丙 課程性質︰必帶 課程教師︰何國榮 開課學院：工學院 開課系所︰化工系 考試日期（年月日）︰2011/11/16 考試時限（分鐘）：110 是否需發放獎勵金：是 （如未明確表示，則不予發放） 試題 : 1.Explain the purpose of (a)sampling and (b)sample preparation 2.In the analysis of coffeine in chocolate bars(Chapter 0), explain (a)the reason of cooling the sliced chocolate (b)the reason of using petroleum ether as the solvent in the extraction step (c)the reason of not removing sugar before HPLC analysis 3.Describe the approachs for minimizing the uncertainty due to measurement errors. 4.Describe the relationship between "accuracy" and random error. 5.To deliver a volume of 100mL using an uncalibrated 25mL pipet, describe the uncertainty due to the systematic error and random error. 6.Write each answer with the correct number of digits. (a)log(4.218*10^12) (b)10^2.384 (c)antilog(-3.22) 7.Find the absolute and percent relative uncertainty and express each answer with a reasonable number of significant figure. (a)91.3(±1.0)*40.3(±0.2)/21.1(±0.2) (b)log[3.14(±0.05)] 8.Explain that five standard solutions are often prepared in the construction of calibration curve. 9.Describe the conditions of using standard addition in quantitative analysis. 10.Describe "matrix effect" in quantitative analysis. 11.Explain (a)the purpose of significant test (b)the effect of n to the conclusion of the test 12.Explain that strong acid and strong base is nit often used as a buffer solution. 13.Please show that under the conditions of Ka/C<2.5*10^-3, the dissociation of weak acid is less than 5%. α =[A-]/C A- HA 14.Explain the advantage of using a pH meter in acid-base titration. 15.students measured the concentration of HCl in a solution by titrating with different indicators to find the end point. Indicator Mean HCl concentration(M) Number of measurements ±standard deviation 1.Bromothymol blue 0.09565±0.00225 28 2.Methyl red 0.08686±0.00098 18 Is the difference between indicators 1 and 2 significant at the 95% confidence level? 附公式: __ __ _______________ t =|X1-X2|/√s1^2/n1+s2^2/n2 cal __ __ ____________ t =|X1-X2|/S )√n1n2/(n1+n2) cal pooled degree of freedom=(s1^2/n1+s2^2/n2)^2/((s1^2/n1)^2/(n1-1)+(s2^2/n2)^2/(n2-1)) ________________________________ S =√Σ(xi-x1)^2Σ(xj-x2)^2/(n1+n2-2) pooled _________________________________ =√(s1^2(n1-1)+s2^2(n2-1))/(n1+n2-2) 另含 t table, F table --

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