Analytical Chemistry PDF

Analytical chemistry Dr. Imad Younus Hasan Analytical chemistry is the branch of chemistry that deals with the analysis of different substances, and it involves the separation, identification, and the quantification of matter. by using of...

Analytical chemistry Dr. Imad Younus Hasan Analytical chemistry is the branch of chemistry that deals with the analysis of different substances, and it involves the separation, identification, and the quantification of matter. by using of classical methods along with modern scientific instruments to achieve all these purposes. Analytical chemistry is often described as the area of chemistry responsible for: 1- Characterizing the composition of matter, both qualitatively and quantitatively. 2- Improving established analytical methods. 3- Extending existing analytical methods to new types of samples. 4- Developing new analytical methods for measuring chemical phenomena. The scope of analytical chemistry: *The science seeks ever-improved means of measuring the chemical composition of natural and artificial materials by using techniques to identify the substances that may be present in a material and to determine the exact amounts of the identified substance. *Analytical chemistry involves the analysis of matter to determine its composition and the quantity of each kind of matter that is present. *Analytical chemists detect traces of toxic chemicals in water and air. *A detection of the component in qualitative analysis can be the basis of the method or the procedure of its quantitative analysis. *The reaction may be incomplete in qualitative analysis, while in quantitative analysis the reaction should be complete and give clear and known products. Analytical chemistry consists of: A- Qualitative analysis: which deals with the identification of elements, ions, or compounds present in a sample (tells us what chemicals are present in a sample). B- Quantitative analysis: which is dealing with the determination of how much of one or more constituents is present (tells how much amounts of chemicals are present in a sample). This analysis can be divided into three types: 1- Volumetric analysis (Titrimetric analysis): is measured the volume of a solution containing sufficient reagent to react completely with the analyte. 2- Gravimetric analysis: Gravimetric methods, determine the mass of the analyte or some compound chemically related to it. 3- Instrumental analysis: These methods are based on the measurement of physical or chemical properties using special instruments. These properties are related to the concentrations or amounts of the components in the sample. These methods are compared directly or indirectly with typical standard methods. These methods consist of: a- Spectroscopic methods: are based on measurement of the interaction between electromagnetic radiation and analyte atoms or molecules or on the production of such radiation by analytes (ultraviolet, visible, or infrared), fluorimetry, atomic spectroscopy (absorption, 1 Analytical chemistry Dr. Imad Younus Hasan emission), mass spectrometry, nuclear magnetic resonance spectrometry (NMR), X-ray spectroscopy (absorption, fluorescence). b- Electroanalytical methods: involve the measurement of such electrical properties that wanted to be determined, such as pH measurements, electrodeposition, voltammetry, thermal analysis, potential, current, resistance, and quantity of electrical charge. c- Separation methods: They mean the isolation of one component or more from a mixture of components in solid, liquid and gas cases. These methods are included with instrumental methods since the instruments and equipment's are used in separation processes. These methods involve precipitation, volatilization, ion exchange, extraction with solvent and various chromatographic methods. Solution A solution is defined by IUPAC as “ A liquid or solid phase containing more than one substance, when for convenience one (or more) substance, which is called the solvent, is treated differently from the other substances, which are called solutes. Homogeneous solution means that the components of the mixture form a single phase. Heterogeneous solution means that the components of the mixture are of different phase. Common examples of solutions are sugar or salt table in water and salt in water solutions, soda water, etc. In a solution, all the components appear as a single phase. There is particle homogeneity i.e. particles are evenly distributed. This is why a whole bottle of soft drink has the same taste throughout. Classification of solutions according to amount of solute: 1- Unsaturated solutions: if the amount of solute dissolved is less than the solubility limit, or if the amount of solute is less than capacity of solvent. 2- Saturated solutions: is one in which no more solute can dissolve in a given amount of solvent at a given temperature, or if the amount of solute equal to capacity of solvent. 2 Analytical chemistry Dr. Imad Younus Hasan 3- Super saturated solutions: solution that contains a dissolved amount of solute that exceeds the normal solubility limit (saturated solution). Or a solution contains a larger amount of solute than capacity of solvent. This it's occurs when the solution is heated to a high temperature. Classification of solution based on solute particle size: 1- True solution: A homogeneous mixture of two or more substances in which substance (solute) has a particle size less than 1 nm dissolved in solvent. Particles of true solution cannot be filtered through filter paper and are not visible to naked eye (NaCl in water). 2- Suspension solution: heterogeneous mixtures which settles on standing and its components can be separated by filtrating (Amoxcycilline Antibiotics), particle of solute visible to naked eye. 3- Colloidal solution: homogeneous mixture which does not settle on standing, nor are their components filterable, solute particle visible with electron microscope (milk). The Mole The mole is an amount unit similar to familiar units like pair, dozen, gross, etc. It provides a specific measure of the number of atoms or molecules in a bulk sample of matter. A mole is defined as the amount of substance containing the same number of discrete entities (such as atoms, molecules, and ions) as the number of atoms in a sample of pure 12C weighing exactly 12 g. One Latin connotation for the word “mole” is “large mass” or “bulk,” which is consistent with its use as the name for this unit. The mole provides a link between an easily measured macroscopic property, bulk mass, and an extremely important fundamental property, number of atoms, molecules, and so forth. The number of entities composing a mole has been experimentally determined to be 6.02214179×1023, a fundamental constant named Avogadro’s number (NA) or the Avogadro constant in honor of Italian scientist Amedeo Avogadro. This constant is properly reported with an explicit unit of “per mole,” a conveniently rounded version being 6.022 * 1023. Based on that 𝑛𝑜. 𝑜𝑓 𝑢𝑛𝑖𝑡𝑠 (𝑖𝑜𝑛𝑠, 𝑎𝑡𝑜𝑚𝑠, 𝑚𝑜𝑙𝑒𝑐𝑢𝑙𝑒𝑠) = 𝑛𝑜. 𝑜𝑓 𝑚𝑜𝑙𝑒 𝑥 𝐴𝑣𝑜. 𝑛𝑜. 3 Analytical chemistry Dr. Imad Younus Hasan Moles of elements in a mole of a compound Moles of an element in a mole of a compound is equivalent to atoms of the element in a molecule or formula unit of the compound. For example, in 1 mole of glucose (C6H12O6) there are 6 moles of carbon, 12 moles of hydrogen, and 6 moles of oxygen. Each of these equalities between a mole of a substance and the moles of the element in it gives two conversion factors for the calculations. 4 Analytical chemistry Dr. Imad Younus Hasan The molar mass of atoms of an element The atomic mass listed in the periodic table is the molar mass of atoms of the element in g.mol-1. For example, the atomic mass of H listed in the periodic table is 1.008, so the molar mass of H is 1.008 g.mol- 1. Similarly, the atomic mass of O listed in the periodic table is 15.999, and the molar mass of O is 15.999 g.mol-1. The molar mass of molecules of an element The molar mass of molecules of an element is the sum of atomic mass of atoms in the molecule expressed in g.mol-1. For example, the molar mass of H2 is 1.008 g.mol-1 + 1.008 g.mol-1 = 2.016 g.mol-1 The molar mass of a compound The molar mass of a compound is the sum of the atomic masses of all the atoms in the molecular formula or formula unit of the compound. For example, the molar mass of water (H2O) is the sum of the molar mass of two hydrogen atoms + the molar mass of one oxygen atom, i.e., 2x1.008 g.mol-1 H + 15.999 g.mol-1 O = 18.02 g.mol-1 H2O. In other words, to calculate the molar mass of a compound, take the atomic masses of the constituent elements from a periodic table, multiply them with the number of atoms of the element in the formula of the compound, and then add these numbers, as explained in the following examples. Note that the unit g.mol-1 can also be written as: g/mol-1. 5 Analytical chemistry Dr. Imad Younus Hasan Conversion from grams to moles and moles to grams of a substance The molar mass in g.mol-1 is a conversion factor converting the amount of a substance in moles to the mass of the substance in grams. Reciprocal of the molar mass in g.mol-1 is a conversion factor converting the mass of a substance in grams to the amount of the substance in moles. The conversions are explained in the following examples. 6 Analytical chemistry Dr. Imad Younus Hasan 7 Analytical chemistry Dr. Imad Younus Hasan 8 Analytical chemistry Dr. Imad Younus Hasan 9 Analytical chemistry Dr. Imad Younus Hasan 10 Analytical chemistry Dr. Imad Younus Hasan 11 Analytical chemistry Dr. Imad Younus Hasan 12 Analytical chemistry Dr. Imad Younus Hasan Methods of Expressing Concentration Concentration refers to the amount of a substance present in a given volume of solution or mixture. There are several ways to express concentration, each suited for different scientific or practical purposes. Here are some common methods 13 Analytical chemistry Dr. Imad Younus Hasan 14 Analytical chemistry Dr. Imad Younus Hasan 15 Analytical chemistry Dr. Imad Younus Hasan 16 Analytical chemistry Dr. Imad Younus Hasan 17 Analytical chemistry Dr. Imad Younus Hasan 18 Analytical chemistry Dr. Imad Younus Hasan 19 Analytical chemistry Dr. Imad Younus Hasan 20 Analytical chemistry Dr. Imad Younus Hasan 21 Analytical chemistry Dr. Imad Younus Hasan See this video for information (https://youtu.be/-uBCmBOVmak) (https://www.youtube.com/watch?v=U5oOnL7NCgk) 22 Analytical chemistry Dr. Imad Younus Hasan https://youtu.be/774eK8qrotw https://youtu.be/GSI-w0ocbxU https://youtu.be/d6RMKC19F9c 23 Analytical chemistry Dr. Imad Younus Hasan https://youtu.be/tiYXUATraIw https://youtu.be/CM-7IqBsx3M 24 Analytical chemistry Dr. Imad Younus Hasan 25 Analytical chemistry Dr. Imad Younus Hasan 26 Analytical chemistry Dr. Imad Younus Hasan 27 Analytical chemistry Dr. Imad Younus Hasan 28 Analytical chemistry Dr. Imad Younus Hasan 29 Analytical chemistry Dr. Imad Younus Hasan 30 Analytical chemistry Dr. Imad Younus Hasan 31 Analytical chemistry Dr. Imad Younus Hasan. 32 Analytical chemistry Dr. Imad Younus Hasan 33 Analytical chemistry Dr. Imad Younus Hasan 34 Analytical chemistry Dr. Imad Younus Hasan 35