定量化学分析

章节摘录

插图：Gravimetry, based on mass measurement, includes precipitation gravimetry, volatilizationgravimetry, and electrogravimetry. In precipitation gravimetric analysis, the mass ofthe product of the chemical reaction related to the analyte, which is the sparinglysoluble and pure precipitate, is measured with an analytical balance. For example, abarium sulfate gravimetric method for determining sulfur content in iron ores isrecommended by the International Organization for Standardization （ISO 4689.1986,Iron ores——determination of sulfur content——barium sulfate gravimetric method）.After sample preparation, the sulfur in the sample is converted to sulfate, an excessof barium chloride （BaCl） is added to an aqueous solution of the sample to cause theprecipitation of the sulfate as barium sulfate （BaSo）. The precipitate （BaSo） isthen filtered, washed to remove impurities, heated, and weighed to obtain the finalmass of BaSO4. Precipitation gravimetry is usually suitable for samples with an analytegreater than 1%.Volumetric analysis （also volumetric titration） is a quantitative chemical analysisthat is used to determine the unknown concentration of a known reactant.  Astandard solution is added from a buret to react with the analyte until the titration iscomplete, i. e. , the endpoint is reached as determined by an indicator. In volumetricanalysis, the volume measured is used to calculate the concentration of the analyte.For example, a hydrochloric acid （HC1） standard solution added from a buret can beused to determine the concentration of sodium hydroxide （NaOH） in a solution usingmethyl orange （MO） as the indicator. After the neutralization reaction reaches apoint when all the NaOH has just reacted with HC1, an additional very small amount（about one half drop） of HC1 changes the final solution from basic to acidic and themethyl orange indicator changes its color from yellow to orange.Volumetric analysis are classified by the type of reactions occurring, e.g., acid-base titration （neutralization titration）, complexometric titration, redox titrationand precipitation titration.

前言

This text brings together the individuals and the desire to develop a text forundergraduate students who have English as a second language. Our initial focus wasundergraduate students with chemistry major in the College of Chemistry and MolecularEngineering, Peking University, Beijing, China, but now we hope and expect that otherundergraduate students may be able to learn more easily with this text as they cope withthe English language and the essentials of analytical chemistry.Lecture Series Leading to Text:The one semester course in analytical chemistry in English for undergraduatestudents was initiated by Professor Li Ke'an in February 2005 with Dr. Li Na as thepresenter of one 2 hour lecture each week for 15 weeks. The size of the lecture roomlimited the number of students to 50.Each year the students prepare presentations of their science project reports.The audience of their peers grades the oral presentations of those students whovolunteered and were selected to give oral presentations.  Competition for beingincluded among the oral presenters has been impressive. Student discussion, gradingof the presenters and the presentations bring forth a profound bonding. Each of us inthe lecture room feels the shoes worn by another.As we introduced different examples and illustrations to the lecture series, thesequickly became ideas for the coming analytical chemistry text.  In Chapter 1," theHuman Genome Project was used to show the power and success possible whenanalytical chemists join forces to bring the minds and resources of the academiccommunity to focus on a goal. The project is indeed a road map of problem solvingusing new and different technologies plus automation to resolve analytical roadblocks to meet the time constraints of the Genome Project thus opening researchopportunities for decades.  A global environmental need brought together anothergroup of scientists in the concluding Chapter 10 to address the ever present need tomonitor drinking water contamination throughout the world. We selected arsenic asone example of the world-wide need for simple, sensitive, cost effective analyticalmethods to monitor drinking water.

内容概要

作者：LiNa (美国)Jpohn J.Hefferren   LiKe'an

书籍目录

CHAPTER 1  INTRODUCTION OF ANALYTICAL CHEMISTRY  1.1  What is Analytical Chemistry    2  1.2  Steps in the Development of an Analytical Method     5  1.3  Classification of Quantitative Analytical Methods    7    1.3.1  Chemical Analysis     7    1.3.2  Instrumental Analysis     8  1.4  Principles of Volumetric Titration    8    1.4.1  Basic Terms     9    1.4.2  Requirements of Titration Reactions     9    1.4.3  Classification of Titration Processes     10    1.4.4  Primary Standards and Standard Solutions     10    1.4.5  Basic Apparatus in Chemical Analyses     11  1.5  Calculations in Volumetric Titration     15    1.5.1  Preparation of Standard Solutions     15    1.5.2  Titration Results     18CHAPTER 2  DATA ANALYSIS    22  2.1  Error and Classification    23    2.1.1  Accuracy and Precision      23    2.1.2  Errors and Deviation     24    2.1.3  Systematic and Random Errors     25  2.2  Distribution of Random Errors    26    2.2.1  Frequency Distribution     27    2.2.2  Normal Distribution     28    2.2.3  Predicting the Probability of Random Errors--Area under Gaussian Curve     30  2.3  Statistical Data Treatment     31    2.3.1  Estimation of Population Mean (μ) and Population Standard Deviation (α)     31    2.3.2  Confidence Interval for Population Mean     34    2.3.3  Statistical Aids to Hypothesis Testing     37    2.3.4  Detection of Gross Errors     42  2.4  Propagation of Error    43    2.4.1  Systematic Errors     43    2.4.2  Random Errors (Standard Deviation)      43    2.4.3  Maximum Errors (ER)     44    2.4.4  Distribution of Errors     44  2.5  Significant Figure Convention    45    2.5.1  Significant Figures     45    2.5.2  Numerical Rounding in Calculations     47CHAPTER 3  ACID-BASE EQUILIBRIUM    50  3.1  Equilibrium Constants and Effect of Electrolytes    51  3.2  Acid-base Reactions and Equilibria     53    3.2.1  Acid and Base--Bronsted Concept     53    3.2.2  Dissociation of Acid or Base and Acid-base Equilibria     55    3.2.3  Magnitude of Dissociating Species at a Given pH： x-values      57  3.3  Solving Equilibrium Calculations Using pH Calculations as an Example     61    3.3.1  General Approaches (Systematic Approaches)     61    3.3.2  pH Calculations     64  3.4  Buffer Solutions    71    3.4.1  pH Calculations of Buffer Solutions     71    3.4.2  Buffer Capacity     72    3.4.3  Preparation of Buffers      74CHAPTER 4  ACID-BASE TITRATION    78  4.1  Acid/Base Indicators    79    4.1.1  Principle      79    4.1.2  Examples     80    4.1.3  Titration Errors     82    4. 1.4  Factors Influencing Performance     82  4.2  Titration Curves and Selection of Indicators     83    4.2.1  Strong Acids (Bases)     83    4.2.2  Monoprotic Acids (Bases)     86    4.2.3  Strong and Weak Acids (Bases)      91    4.2.4  Polyfunctional Weak Acids (Bases)      92    4.2.5  Mixture of Weak Acids (Bases)     95  4.3  Titration Error Calculations     95    4.3.1  Strong Acids (Bases)     95    4.3.2  Monoprotic Weak Acids (Bases)      96    4.3.3  Polyfunctional Acids (Bases)      97  4.4  Preparation of Standard Solutions    98    4.4.1  Standard Acid Solutions     98    4.4.2  Standard Base Solutions     99    4.4.3  The Carbonate Error     100  4.5  Examples of Acid-base Titrations     101    4.5.1  Determination of Total Alkalinity      101    4.5.2  Determination of Nitrogen     102    4.5.3  Determination of Boric Acid     103  4.6  Acid-base Titrations in Non-aqueous Solvents     104    4.6.1  Non-aqueous Solvents     104    4.6.2  Examples of Non-aqueous Titrations     105CHAPTER 5  COMPLEXATION REACTION AND COMPLEXOMETRIC TITRATION    108  5.1  Complexes and Formation Constants    109    5.1.1  Formation Constants     109    5.1.2  Concentration of MLn in Complexation Equilibria     111    5.1.3  Ethylenediaminetetraacetic Acid (EDTA) and Metal-EDTA Complexes     113    5.1.4  Side Reaction Coefficients and Conditional Formation Constants in Complexation Reactions      115  5.2  Metallochromic Indicators     122    5.2.1  How a Metallochromic Indicator Works     122    5.2.2  Color Transition Point pM ((pM)t) for Metallochromic Indicators     123    5.2.3  Frequently Used Metallochromic Indicators     125  5.3  Titration Curves and Titration Errors     126    5.3.1  Titration Curves     126    5.3.2  Titration Errors     128    5.3.3  pH Control in Complexometric Titrations     129  5.4  Selective Titrations of Metal Ions in the Presence of Multiple Metal Ions    130       5.4.1  Selective Titration by Regulating pH     131       5.4.2  Selective Titration Using Masking Reagents     133  5.5  Applications of Complexometric Titrations    137    5.5.1  Buffer Selection in Complexometric Titrations     !37    5.5.2  Titration Methods and Applications     138    5.5.3  Preparation of Standard Solutions     142CHAPTER 6  REDOX EQUILIBRIUM AND TITRATION     146  6.1  Standard Electrode Potentials, Formal Potentials and Redox Equilibria    147    6.1.1  Standard Electrode Potentials     147    6.1.2  The Nernst Equation and Formal Potentials     149    6.1.3  Factors Affecting the Formal Potential     150    6.1.4  The Equilibrium Constant of Redox Reaction     154  6.2  Factors Affecting the Reaction Rate     155    6.2.1  Concentrations     156    6.2.2  Temperature     157    6.2.3  Catalysts and Reaction Rate     157    6.2.4  Induced Reaction     157  6.3  Redox Titrations    158    6.3.1  Constructing Redox Titration Curves     158    6.3.2  Indicators     162    6.3.3  Auxiliary Oxidizing and Reducing Agents     164  6.4  Examples of Redox Titrations    165    6.4.1  Potassium Permanganate (KMnO4)      165    6.4. 2  Potassium Dichromate (K2Cr2O7)      168    6.4. 3  Iodine: Iodimetry and Iodometry     169    6.4. 4  Potassium Bromate (KBrO3)      173    6.4.5  Ceric Sulfate (Ce(SO4)2)      174CHAPTER 7  PRECIPITATION EQUILIBRIUM, TITRATION, AND GRAVIMETRY    177  7.1  Precipitation Equilibria and Solubility    178    7.1.1  Solubility of Precipitates in Pure Water     178    7.1.2  Ionic Strength and the Solubility of Precipitates     178    7.1.3  Common Ion and the Solubility of Precipitates     179    7.1.4  pH and the Solubility of Precipitates     179    7.1.5  Complexing Agents and the Solubility of Precipitates     182  7.2  Precipitation Titrations    184    7.2.1  Titration Curves     184    7.2.2  Examples of Methods Classified by Endpoint Indication     186    7.2.3  Preparation of Standard Solutions     189  7.3  Precipitation Gravimetry    190    7.3.1  Classification of Gravimetric Methods of Analysis     190    7.3.2  General Procedure and Requirements for Precipitation     190    7.3.3  Precipitate Formation     192    7.3.4  Obtaining High Purity Precipitates      193    7.3.5  Experimental Considerations     197    7.3.6  Examples of Organic Precipitating Reagents     200CHAPTER 8  SPECTROPHOTOMETRY    206  8.1  Principle of Spectrochemical Analysis     207    8.1.1  Properties of Electromagnetic Radiation     207    8.1.2  Interaction of Electromagnetic Radiation with Matter     208    8.1.3  Beer's Law, the Quantitative Principle of Light Absorption     213    8.1.4  Limitations to Beer's Law      216  8.2  Principles of Instrumentation     217    8.2.1  Instrumentation     217    8.2.2  Instrumental Errors in Absorption Measurement     226  8.3  Applications of Spectrophotometry    226    8.3.1  Single Component Analyses     226    8.3.2  Multicomponent Analyses     228    8.3.3  Spectrophotometric Titrations     230    8.3.4  Studies of Complex Formation in Solutions     231    8.3.5  Measurements of Dissociation Constants of Organic Acids/Bases     233CHAPTER 9  INTRODUCTION TO ANALYTICAL SEPARATION     238  9.1  General Considerations of Separation Efficiency     239  9.2  Separation by Precipitation    241    9.2.1  Inorganic Precipitants     241    9.2.2  Organic Precipitants     242    9.2.3  Coprecipitation of Species in Trace Amounts for Separation     243    9.2.4  Improving the Selectivity of Precipitation Separation     244  9.3  Separation by Extraction     245    9.3.1  Principles for Liquid-liquid Extraction     245    9.3.2  Percent Extraction      247    9.3.3  Extraction of Inorganic Species      249    9.3.4  Other Extraction Methods     254  9.4  Separation by Ion Exchange     257    9.4.1  Ion Exchange Resins     257    9.4.2  Cross-linkage and Exchange Capacity     259    9.4.3  Ion Exchange Equilibria     260    9.4. 4  Applications of Ion Exchange Separation     261  9.5  Separation by Chromatography    263    9.5.1  Classification     263    9.5.2  Chromatogram     264    9.5.3  Column Chromatography     265    9.5.4  Planar Chromatography     266CHAPTER 10  SOLVING A REAL ANALYTICAL PROBLEM    271  10.1  Definition of the Analytical Problem    272  10.2  Literature Review     273  10.3  Choosing a Method    275  10.4  Developing and Evaluating the Method    276    10.4.1  Selectivity     276    10.4.2  Accuracy     277    10.4.3  Sensitivity and Linear Dynamic Range     279  10.5  Conclusion     280APPENDICES       281  Appendix A  References     281  Appendix B  Indicators    283  Appendix C  Activity Coefficients(г) for Ions at 25℃     285  Appendix D  Constants for Acid-base, Complexometric, Redox, and Precipitation Titrimetry    286  Appendix E  Molecular Masses     299ANSWERS   302INDEX    305PERIODIC TABLE OF THE ELEMENTS    309

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《定量化学分析》是由北京大学出版社出版的。

作者简介

《定量化学分析》内容简介：This text brings together the individuals and the desire to develop a text for undergraduate students who have English as a second language. Our initial focus wasundergraduate students with chemistry major in the College of Chemistry and MolecularEngineering, Peking University, Beijing, China, but now we hope and expect that otherundergraduate students may be able to learn more easily with this text as they cope withthe English language and the essentials of analytical chemistry.

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