General Chemistry for Engineers

Jeffrey Gaffney, Nancy Marley

• Verlag: Elsevier
• Jahr: 2017
• ISBN:
  9780128104446
• Thema: Technology & Engineering
• Thema: Chemical & Biochemical Engineering

General Chemistry for Engineers explores the key areas of chemistry needed for engineers. This book develops material from the basics to more advanced areas in a systematic fashion. As the material is presented, case studies relevant to engineering are included that demonstrate the strong link between chemistry and the various areas of engineering.

• Serves as a unique chemistry reference source for professional engineers
• Provides the chemistry principles required by various engineering disciplines
• Begins with an 'atoms first' approach, building from the simple to the more complex chemical concepts
• Includes engineering case studies connecting chemical principles to solving actual engineering problems
• Links chemistry to contemporary issues related to the interface between chemistry and engineering practices

Chapter 1

Introduction

Abstract

This chapter is an introduction to chemistry and chemical methods for engineering students. It describes how chemistry is used in engineering and how chemical principles aid engineers in the choice of materials for a particular application. Both concepts and guidelines of “green chemistry” and “green engineering” are reviewed for the optimization of sustainability in the design of products, processes, and systems. Scientific measurement principles including accuracy, precision, and sources of errors are explained. A comparison between scientific notation and engineering notation is given with an emphasis on significant figures. The SI system of base units and how they are converted to derived units is discussed. Five physical states of matter are described in terms of their physical and molecular characteristics. The classification of matter according to its physical and chemical state and separation methods used for mixtures based on differences in physical properties of the pure substances are reviewed.

Keywords

Green engineering; Scientific notation; Significant figures; Measurement errors; SI units; States of matter; Classification of matter; Solutions; Suspensions; Separation methods

Outline

1.1 The Role of Chemistry in Engineering

1.2 Green Engineering

1.3 Measurement and Calculations

1.4 The Physical States of Matter

1.5 Classification of Matter

1.6 Separation of Mixtures

Important Terms

Study Questions

Problems

1.1 The Role of Chemistry in Engineering

Engineering has been called an applied science. The various disciplines of engineering focus on the design and construction of structures, machines, apparatus, or processes to solve problems. This requires an in-depth knowledge of the properties of materials and a broad knowledge of science and mathematics. Although engineers use scientific principles in their designs, they must also consider economics and safety issues as well as efficiency, reliability, and ease of construction. In many cases, the best choice of materials for a design may not be economically feasible and compromises must be made.

The Accreditation Board for Engineering and Technology (ABET) lists 28 different areas of engineering in their 2012–13 “Criteria for Accrediting Engineering Programs.” These range from Chemical, Biochemical, Biomolecular Engineering, which use chemical principles on a daily basis, to Systems Engineering, which is typically not directly involved with chemical principles. In between these two extremes are disciplines that require a basic knowledge of chemistry, materials science, and/or environmental science to fully understand the problems they are to solve. Even those areas of engineering that do not use chemical principles directly are involved with them indirectly because chemical principles dictate the properties and behavior of materials, electrical systems, and electronic devices, as well as energy production and environmental impacts.

An engineer uses the macroscopic properties of materials such as the hardness, strength, malleability, or conductivity to determine the appropriate choice of materials for a specific project. Many times, these macroscopic properties are experimentally measured. Chemistry is the study of the properties and behavior of matter on the microscopic or the atomic/molecular scale. This description of matter on the microscopic scale lays the foundation for the underlying reasons for the properties and behavior of materials observed on the macroscopic scale. By understanding the atomic and molecular forces that lead to the basic properties of materials, their macroscopic properties and their reactions to external stresses can be better understood and predicted.

Case Study: Scratch Hardness

The scratch hardness of a material is the measure of its resistance to being scratched or abraded by a sharp object. This is a prime consideration in choosing materials for construction of mechanical tools or machines where friction is an issue. One of the oldest measures of hardness is the Mohs scale, created in 1812 by the German geologist Friedrick Mohs. This scale was originally designed to describe the hardness of minerals with diamond as the hardest known mineral at a value of 10 and talc as the softest known mineral with a value of 1. Other minerals were given intermediate values based on the ability of one mineral to scratch another mineral.

Table 1.1 lists the scratch hardness of some common materials. The minerals specified by Mohs are listed in the Table along with some other materials which were determined later to fall between the levels designated by Mohs. As we shall see in later Chapters, this trend in scratch hardness can be explained by an understanding of the types of bonding between atoms in the materials on the microscopic scale. Although diamonds and graphite are both composed of carbon atoms, the hardness of the two materials differs by almost a factor of 10 on the Mohs scale. However, the Mohs scale is a relative designation and is not a linear scale. The difference between the hardness of graphite and diamond is much larger ...