Chapter 5 Working with Chemicals

The effect of a detonation depends on the shock wave, that is, an immediate peak overpressure followed by a longer period with an underpressure. The strength of the shock wave depends on the mass of the detonating materials. Detonations are mostly induced by initiation sources. In some cases, a deflagration may make a transition into a detonation. Working with chemicals and systems under plant conditions where a detonation can be induced is NOT recommended. Whether or not a chemical or chemical system can detonate can be determined only by specific tests as outlined in Chapter 2. 

This chapter provides an introduction, which, hopefully, will enable chemists and engineers to appreciate the major Safety/Health issues faced by people working with chemicals. The most immediately devastating are obviously explosion and fire. Adverse health effects resulting from the exposure of people to certain chemicals can also be immediate (e.g., exposure to methyl isocyanate in Bhopal), but health effects can also take time to manifest themselves. In view of the unknowns, it is best to maintain caution in all situations even though, putting matters into perspective, exposure to many chemicals (solvent vapors are the most common) can be tolerated... 

Two types of hazards are associated with the use of chemicals—hazards that are a direct result of the physical and reactive properties of a chemical, and health hazards resulting from the biological properties. This chapter summarises hazards that are associated with working with chemicals in a laboratory, and highlights some sources of hazard information for carrying out hazard and risk assessments. 

Up to this point in Chapter 5, we have been concerned with individual formula units or molecules. In this lesson we will discuss how we represent multiple formula units and molecules, in preparation for working with entire chemical equations. You have probably had some experience working with chemical equations before, possibly in a biology class, so this may not be entirely new to you. What may be new to you is the level of understanding that you will be expected to demonstrate, in a variety of ways, now that you are studying chemistry. 

This chapter covers existing DOE and other federal requirements for the training of employees involved in the handling, storage and use of chemicals. State and local requirements are not included. The requirements included here apply to all locations that use and/or store chemicals or chemical products. The key message of this chapter is that those who work with chemicals must be appropriately trained to recognize both the hazards of the chemicals they work with and the ways in which they may protect themselves from those hazards - i.e., they must be trained to safely perform their jobs and follow prescribed procedures. 

Select appropriate procedures to minimize exposure. Use the "basic prudent practices for handling chemicals," which are discussed in Chapter 5, section 5.C, for all work with chemicals in the laboratory. In addition, determine whether any of the chemicals to be handled in the planned experiment meet the definition of a particularly hazardous substance due to high acute toxicity, carcinogenicity, and/ or reproductive toxicity. If so, consider the total amount of the substance that will be used, the expected frequency of use, the chemical s routes of exposure, and the circumstances of its use in the proposed experiment. As discussed in this chapter, use this information to determine whether it is appropriate to apply the additional procedures for work with highly toxic substances and whether additional consultation with safety professionals is warranted (see Chapter 5, section 5.D). 

In section 5.D, additional special procedures are presented for work with highly toxic substances. How to determine when these additional procedures are necessary is discussed in detail in Chapter 3, section 3.C. Section 5.E gives detailed special procedures for work with chemicals that pose risks due to biohazards and radioactivity section 5.F, flammability and section 5.G, reactivity and explosibility. Special considerations for work with compressed gases are the subject of section 5.H. 

National Research Council. Prudent Practices in the Laboratory Handling and Managementl of Chemicals. Chapter 6. Working with Chemicals. Section 6.G Working with Highly Reactive or Explosive Chemicals. National Academy Press, Washington, DC, 2011, pp. 105-146. 

The chapter on Radioactive chemicals (Chapter 11) has been updated. Considerations of safety in design (Chapter 12) are presented separately from systems of work requirements, i.e. Operating procedures (Chapter 13). Tlie considerations for Marketing and transportation of hazardous chemicals are now addressed in two separate chapters (Chapters 14 and 15). Chemicals and the Environment are now also covered in two chapters (Chapters 16 and 17) to reflect the requirement that the impact of chemicals on the environment should be properly assessed, monitored and controlled. Although a substantial contribution to atmospheric pollution is made by emissions from road vehicles and other means of transport, and this is now strictly legislated for, this topic is outside the scope of this text. Chapter 18 provides useful conversion factors to help with the myriad of units used internationally. 

To develop a terse, broad description of mechanical, physical, and chemical processes in solids, this book is divided into five parts. Part I contains one chapter with introductory material. Part II summarizes aspects of mechanical responses of shock-compressed solids and contains one chapter on materials descriptions and one on experimental procedures. Part III describes certain physical properties of shock-compressed solids with one chapter on such effects under elastic compression and one chapter on effects under elastic-plastic conditions. Part IV describes work on chemical processes in shock-compressed solids and contains three chapters. Finally, Part V summarizes and brings together a description of shock-compressed solids. The information contained in Part II is available in much better detail in other reliable sources. The information in Parts III and IV is perhaps presented best in this book. 

The isolation and identification of 4 radioactive elements in minute amounts took place at the turn of the century, and in each case the insight provided by the periodic classification into the predicted chemical properties of these elements proved invaluable. Marie Curie identified polonium in 1898 and, later in the same year working with Pierre Curie, isolated radium. Actinium followed in 1899 (A. Debierne) and the heaviest noble gas, radon, in 1900 (F. E. Dorn). Details will be found in later chapters which also recount the discoveries made in the present century of protactinium (O. Hahn and Lise Meitner, 1917), hafnium (D. Coster and G. von Hevesey, 1923), rhenium (W. Noddack, Ida Tacke and O. Berg, 1925), technetium (C. Perrier and E. Segre, 1937), francium (Marguerite Percy, 1939) and promethium (J. A. Marinsky, L. E. Glendenin and C. D. Coryell, 1945). 

No single working fluid has ah these properties and a great many different chemicals have been used over the years. The present situation has been dominated by the need for fluids which are environmentally friendly. This is dealt with in Chapter 3. 

Chemical advances frequently are driven by technology. The discovery that atoms have inner structure was an outgrowth of the technology for working with radioactive materials. In Chapter 2 we describe a famous experiment in which the structure of atoms was studied by bombarding a thin gold foil with subatomic particles. A contemporary example is the use of lasers to study the details of chemical reactions. We introduce these ideas in Chapters 7 and 8. 

In this chapter, we work primarily with pressures in atmospheres or torr, but we use pressures in bars in later chapters when we work with standard chemical conditions. Example illustrates pressure measurement and unit... 

This chapter is concerned with the design and improvement of chemically-active ship bottom paints known as antifouling paints. The aims have been to illustrate the challenges involved in working with such multi-component, functional products and to show which scientific and engineering tools are available. The research in this field includes both purely empirical formulation and test methods and advanced tools including mathematical modelling of paint behaviour. 

It is not practical here, of course, to attempt to list all the chemicals that can be found in the workplace, far less to describe their effects and toxicity. The list, of course, will vary according to the nature of the work. The chemicals found in paint manufacturing, for instance, will be different from those occurring in a foundry. The nature and occurrence of some of the more common of these industrial chemicals, along with their toxic effects, is examined in Chapter 7. 

Although the authors discuss a diversity of interests and chemical approaches, the chapters are connected by a common thread All are concerned with the synthesis and/or reactions of well-defined low molecular weight compounds that are terminated with reactive functional groups. We believe that the information presented not only serves as an excellent introduction to the field, but also is of considerable value to those already working with these systems. 

---