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 treat experimental data?”, “How do we ensure that our results are accurate?”, “How do we obtain a representative sample?”, and “How do we select an appropriate analytical technique?” Before we look more closely at these and other questions, we will first 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 briefly review the use of units and significant figures in analytical chemistry.
- 2.2: Concentration
- Concentration is a general measurement unit stating the amount of solute present in a known amount of solution. Although we associate the terms “solute” and “solution” with liquid samples, we can extend their use to gas-phase and solid-phase samples as well. Table 2.4 lists the most common units of concentration.
- 2.3: Stoichiometric Calculations
- A balanced reaction, which gives the stoichiometric relationship between the moles of reactants and the moles of products, provides the basis for many analytical calculations.
- 2.4: Basic Equipment
- The array of equipment for making analytical measurements is impressive, ranging from the simple and inexpensive, to the complex and expensive. With three exceptions—measuring mass, measuring volume, and drying materials—we will postpone the discussion of equipment to later chapters where its application to specific analytical methods is relevant.
- 2.5: Preparing Solutions
- Preparing a solution of known concentration is perhaps the most common activity in any analytical lab. The method for measuring out the solute and solvent depend on the desired concentration unit and how exact the solution’s concentration needs to be known. Pipets and volumetric flasks are used when a solution’s concentration must be exact; graduated cylinders, beakers and reagent bottles suffice when concentrations need only be approximate. Two methods for preparing solutions are described.
- 2.6: Spreadsheets and Computational Software
- Analytical chemistry is an inherently quantitative discipline. Whether you are completing a statistical analysis, trying to optimize experimental conditions, or exploring how a change in pH affects a compound’s solubility, the ability to work with complex mathematical equations is essential. Spreadsheets, such as Microsoft Excel can be an important tool for analyzing your data and for preparing graphs of your results. Scattered throughout the text you will find instructions for using spreadsheet
- 2.7: The Laboratory Notebook
- Your 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. Maintaining a laboratory notebook may seem like a great deal of effort, but if you do it well you will have a permanent record of your work. Scientists working in academic, industrial and governmental research labs rely on their notebooks to provide a written record.
- 2.E: Basic Tools of Analytical Chemistry (Exercises)
- These are homework exercises to accompany "Chapter 2: Basic Tools of Analytical Chemistry" from Harvey's "Analytical Chemistry 2.0" Textmap.
- 2.S: Basic Tools of Analytical Chemistry (Summary)
- This is a summary to accompany "Chapter 2: Basic Tools of Analytical Chemistry" from Harvey's "Analytical Chemistry 2.0" Textmap.
Thumbnail: A Roberval balance. The pivots of the parallelogram understructure makes it insensitive to load positioning away from center, so improves its accuracy, and ease of use. Image used with permission (CC BY-SA 3.0; Nikodem Nijaki)