Đang chuẩn bị liên kết để tải về tài liệu:
Modern Analytical Cheymistry - Chapter 2

Basic Tools of Analytical Chemistry Trong chương tiếp theo, chúng ta sẽ tìm hiểu về các chi tiết cụ thể của hóa học phân tích. Trong quá trình chúng tôi sẽ hỏi và trả lời những câu hỏi như "Làm thế nào để chúng tôi xử lý dữ liệu thực nghiệm?" "Làm thế nào để chúng ta đảm bảo rằng kết quả của chúng tôi là chính xác"? "Làm thế nào để chúng ta có được một mẫu đại diện?" Và "Làm thế nào để chúng tôi lựa chọn thích hợp Thể phân tích kỹ thuật "Trước khi chúng tôi. | Chapter 2 Basic Tools of Analytical Chemistry I n the chapters that follow we will learn about the specifics of analytical chemistry. In the process we will ask and answer questions such as How do we treat experimental data How do we ensure that our results are accurate How do we obtain a representative sample and How do we select an appropriate analytical technique Before we look more closely at these and other questions we will first review some basic numerical and experimental tools of importance to analytical chemists. II 12 Modern Analytical Chemistry SI units Stands for Système International d Unites. These are the internationally agreed on units for measurements. scientific notation A shorthand method for expressing very large or very small numbers by indicating powers of ten for example 1000 is 1 X 103. 2A Numbers in Analytical Chemistry Analytical chemistry is inherently a quantitative science. Whether determining the concentration of a species in a solution evaluating an equilibrium constant measuring a reaction rate or drawing a correlation between a compound s structure and its reactivity analytical chemists make measurements and perform calculations. In this section we briefly review several important topics involving the use of numbers in analytical chemistry. 2A.1 Fundamental Units of Measure Imagine that you find the following instructions in a laboratory procedure Transfer 1.5 of your sample to a 100 volumetric flask and dilute to volume. How do you do this Clearly these instructions are incomplete since the units of measurement are not stated. Compare this with a complete instruction Transfer 1.5 g of your sample to a 100-mL volumetric flask and dilute to volume. This is an instruction that you can easily follow. Measurements usually consist of a unit and a number expressing the quantity of that unit. Unfortunately many different units may be used to express the same physical measurement. For example the mass of a sample weighing 1.5 g also may .