Measurements are one of the most important things to understand in chemistry as well as other physical sciences. Measurements are not only important in science, but in many fields of work which depend upon science including agriculture, medicine, and other health related fields. In all of these fields, workers are routinely measuring things and reading measured amounts: the area of a plot of land, the weight of a patient, the concentration of a medication, the volume of a measuring device. Misunderstandings of measurement could result in catastrophe in any of these areas. (in fact, miscalculations related to measurements were responsible for several tragedies including a very expensive Mars mission.) There are several important things to understand related to measurements: what they are, their precision, and how to perform calculations with measured numbers. Section 1.1 discusses measurements in terms of numbers and units. Section 1.2 discusses how we explain precision when we report measurements. Section 1.3 discusses how we can use the units of measurements to correctly perform the types of calculations that will be important in this course, and in applications which you will use in whatever field you go into.
- 1.1: Taking Measurements- Numbers and Units
- Chemists measure the properties of matter and express these measurements as quantities. A quantity is an amount of something and consists of a number and a unit. The number tells us how many (or how much), and the unit tells us what the scale of measurement is. For example, when a distance is reported as “5 kilometers,” we know that the quantity has been expressed in units of kilometers and that the number of kilometers is 5.
- 1.2: Significant Figures
- In addition to a number and unit, it is also important to consider significant figures when reporting or reading a measurement. Significant figures tell us something about the precision with which a measurement was made.
- 1.3: Conversions
- Perhaps the most important skill to learn in this class is how to convert between different units of measurement. This skill is not only important in this section, but will continue to come up in almost every chapter of this book.
- 1.E: Measurements (Exercises)
- The following questions are related to the material covered in this chapter, however they may not be presented in the same order that they were in your chapter.