2: Basic Tools of Analytical Chemistry
- Page ID
- 127130
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)In the chapters that follow we will explore many aspects of analytical chemistry. In the process we will consider important questions, such as “How do we extract useful results from experimental data?”, “How do we ensure our results are accurate?”, “How do we obtain a representative sample?”, and “How do we select an appropriate analytical technique?” Before we consider these and other questions, we first must review some basic tools of importance to analytical chemists.
- 2.1: Measurements in Analytical Chemistry
- Analytical chemistry is a quantitative science. Whether determining the concentration of a species, evaluating an equilibrium constant, measuring a reaction rate, or drawing a correlation between a compound's structure and its reactivity, analytical chemists engage in "measuring important chemical things". In this section we review briefly the basic units of measurement and the proper use of significant figures.
- 2.2: Concentration
- This page outlines various units for measuring concentration in solutions, including molarity, formality, normality, molality, and several percentage-based methods. It differentiates between molarity and formality, noting that molarity focuses on chemical species while formality accounts for total concentration without regard to dissociation. It also discusses the rarely used normality and temperature-independent molality.
- 2.3: Stoichiometric Calculations
- The page discusses stoichiometric calculations and their applications in analytical chemistry. It presents examples involving the determination of oxalic acid in rhubarb and disulfiram in Antabuse. The analysis uses stoichiometric relationships derived from balanced chemical reactions to compute amounts of substances. Key steps include calculating moles, converting them to grams or other relevant metrics, and determining percent composition.
- 2.4: Basic Equipment
- This page provides an overview of the equipment used in analytical measurements, specifically focusing on the measurement of mass and volume, as well as the importance of drying samples. It details the use of digital balances for mass measurement, different types of glassware for volume measurement such as graduated cylinders, pipets, and volumetric flasks, and the necessity of accurate calibration.
- 2.5: Preparing Solutions
- This page discusses the preparation of solutions of known concentrations, a common task in analytical labs. It covers the use of pipets and volumetric flasks for precise concentrations and other glassware for approximate concentrations. It explains preparing stock solutions using solids or liquids, and details examples of preparing solutions of NaOH, Cu ion, and acetic acid.
- 2.6: Spreadsheets and Computational Software
- The text emphasizes the significance of quantitative skills and the use of spreadsheets in analytical chemistry, highlighting Microsoft Excel, Calc, and Google Sheets as valuable tools for data analysis and graph preparation. It suggests more advanced software options like R, Mathematica, or Matlab for scientific data handling. The text underscores the importance of intuitive thinking in chemistry and suggests developing this skill alongside technical proficiency for effective problem-solving.
- 2.7: The Laboratory Notebook
- A laboratory notebook is your most important tool when working in the lab. If kept properly, you should be able to look back at your laboratory notebook several years from now and reconstruct the experiments on which you worked.
- 2.8: Problems
- This text provides exercises on significant figures, calculations with chemical formulas, concentrations, and molarities. It challenges readers to determine significant figures in given numbers, round numbers, perform calculations with appropriate significant figures, and solve problems involving molarity, concentration levels, and stoichiometric conversions. Specific chemical and mathematical problems are included for practical understanding.
- 2.9: Additional Resources
- This page provides resources on the SI system of units, helpful references for chemists, considerations for potential changes in SI base units, guides for maintaining laboratory records, instructions for using spreadsheets in chemistry, and a textbook on problem-solving in environmental science.
- 2.10: Chapter Summary and Key Terms
- This chapter covers fundamental numerical and experimental tools in analytical chemistry. It emphasizes using base SI units for measurements like mass and includes significant digits to maintain measurement precision. Concentrations are expressed in various ways, such as molarity and weight percent. Stoichiometric calculations are highlighted for quantitative analyses. Familiarity with lab equipment like balances and pipets is essential, as is the preparation of stock and dilute solutions.