1. Introduction to Analytical Chemistry
Chapter 22
Selected Methods of Analysis

2. Selected Methods of Analysis
This chapter contains detailed directions for performing a variety of chemical analyses. The methods have been chosen to introduce you to analytical techniques that are widely used by chemists.
Your chances of success in the laboratory will greatly improve if you take time before beginning any analysis to read carefully and understand each step in the method and to develop a plan for how and when you will perform each step.

3. Background Information
Before you start an analysis, you should understand the significance of each step in the procedure to avoid the pitfalls and potential sources of error.

4. The Accuracy of Measurements
Generally, measurements that appear in the equation used to compute the results must be performed with maximum precision. The remaining measurements can and should be made less carefully to conserve time.

5. Water
Some laboratories use deionizers to purify water; others employ stills for this purpose. The terms “distilled water” and “deionized water” are used interchangeably in the directions that follow.

6. 22A-3 Delivering an Aliquot
Whenever a buret or pipet is used to deliver a measured volume of solution, the liquid it contains before measurement should have the same composition as the solution to be dispensed.

7. 22A-7 Sampling
In most analytical methods, only a small fraction of the entire population is analyzed.
A laboratory sample taken from the entire batch must be representative of the population.
If p represents the fraction of the particles of the analyte, then 1 – p is the fraction of the second type of particles .

8. 22A-7 Sampling
If a sample of n particles is drawn from the population, the number of particles of the analyte in the sample should be np.
This equation suggests that as the number of particles sampled increases, the relative uncertainty decreases.

9. For discussion and procedures of each analytical methods, please refer to sections in these chapters.

10. THE END