There are a few basic numerical and experimental tools with which you must be familiar. Fundamental measurements in analytical chemistry, such as mass and volume, use base SI units, such as the kilogram. Other units, such as energy, are defined in terms of these base units. When reporting measurements, we must be careful to include only those digits that are significant, and to maintain the uncertainty implied by these significant figures when transforming measurements into results.
The relative amount of a constituent in a sample is expressed as a concentration. There are many ways to express concentration, the most common of which are molarity, weight percent, volume percent, weight-to-volume percent, parts per million and parts per billion. Concentrations also can be expressed using p-functions.
Stoichiometric relationships and calculations are important in many quantitative analyses. The stoichiometry between the reactants and products of a chemical reaction are given by the coefficients of a balanced chemical reaction.
Balances, volumetric flasks, pipets, and ovens are standard pieces of equipment that you will routinely use in the analytical lab. You should be familiar with the proper way to use this equipment. You also should be familiar with how to prepare a stock solution of known concentration, and how to prepare a dilute solution from a stock solution.
2.8.1 Key Terms
parts per million
parts per billion
Gathered here are three types of resources: suggested experiments, mostly from the Journal of Chemical Education and The Chemical Educator, that provide practical examples of concepts in the textbook; additional readings from the analytical literature that extend and supplement topics covered in the textbook. Although primarily intended for the use of instructors, these resources also will benefit students who wish to pursue a topic at more depth.
The following two web sites contain useful information about the SI system of units.
- http://www.bipm.org/en/home/ – The home page for the Bureau International des Poids and Measures.
- http://physics.nist.gov/cuu/Units/index.html – The National Institute of Standards and Technology’s introduction to SI units.
For a chemist’s perspective on the SI units for mass and amount, consult the following papers.
- Freeman, R. D. “SI for Chemists: Persistent Problems, Solid Solutions,” J. Chem. Educ. 2003, 80, 16-20.
- Gorin, G. “Mole, Mole per Liter, and Molar: A Primer on SI and Related Units for Chemistry Students,” J. Chem. Educ. 2003, 80, 103-104.
The following are useful resources for maintaining a laboratory notebook and for preparing laboratory reports.
- Coghill, A. M.; Garson, L. M. (eds) The ACS Style Guide: Effective Communication of Scientific Information, 3rd Edition, American Chemical Society: Washington, D. C.; 2006.
- Kanare, H. M. Writing the Laboratory Notebook, American Chemical Society: Washington, D. C.; 1985.
The following texts provide instructions for using spreadsheets in analytical chemistry.
- de Levie, R. How to Use Excel® in Analytical Chemistry and in General Scientific Data Analysis, Cambridge University Press: Cambridge, UK, 2001.
- Diamond, D.; Hanratty, V. C. A., Spreadsheet Applications in Chemistry, Wiley-Interscience: New York, 1997.
- Feiser, H. Concepts and Calculations in Analytical Chemistry: A Spreadsheet Approach, CRC Press: Boca Raton, FL, 1992.
The following is a classical text emphasizing the application of intuitive thinking when solving problems.
- Harte, J. Consider a Spherical Cow: A Course in Environmental Problem Solving, University Science Books: Sausalito, CA, 1988.
- Murray, R. W. Anal. Chem. 2007, 79, 1765.
- For a review of other types of electronic balances, see Schoonover, R. M. Anal. Chem. 1982, 54, 973A-980A.