Author: Msomi Bora

TOPIC 3: SOIL CHEMISTRY Soil Formation Soil Formation Describe soil formation Soil is formed by the process of weathering. All types of weathering (physical, chemical or biological) result to disintegration of rocks into smaller particles. Air and water enter the space between these particles and chemical changes take place, which lead to the production of chemical substances. Bacteria and plant life soon appear. When plants and animals die, they decay and produce humus. Bacteria and other decomposers play a vital role in the decomposition of plant and animal substrata. The end product of these mechanical, chemical and biological processes is…

TOPIC 2: ORGANIC CHEMISTRY Introduction to Organic Chemistry Organic chemistry is the chemistry of carbon compounds. Due to the ability of carbon to form chains of atoms, and for other atoms or groups of atoms to be attached to these chains, there are a huge number of carbon compounds. All organic compounds contain carbon together with one or more other elements such as hydrogen, oxygen, nitrogen, sulphur and the halogens. Normally every compound of carbon is an organic compound. Even after discovering that these compounds could be synthesized in the laboratory, the definition that they are organic (of organic nature, that is,…

TOPIC 1: NON METALS AND THEIR COMPOUNDS General Chemical Properties of Non Metals The non-metals are very reactive and most of them react with other elements to form different compounds. The following are important chemical properties of non-metals which are connected with their tendency towards electron gain in the course of formation of compounds: 1. The oxide of a non-metal is either acidic or neutral but never basic. The oxide of a non-metal is a covalent compound. Being acidic, it combines with water to form an acid, e.g. 2. A non-metal never replaces hydrogen in an acid to form a…

TOPIC 9: COMPOUNDS OF METALS Metals combine with other substances to form compounds. There is a diversity of metal compounds known. One can make an endless list of the compounds of the metals. In this chapter, we are going to concentrate our efforts on the following compounds of the metals: oxides, hydroxides, carbonates and hydrogencarbonates, nitrates, chlorides and sulphates. Oxides Preparation of Oxides of Some Metals by Direct and Indirect Methods Prepare oxides of some metals by direct and indirect methods All elements except helium, neon and argon form compounds with oxygen. This is because oxygen is quite reactive. Binary…

TOPIC 8: EXTRACTIONS OF METALS Occurrence and Location of Metals in Tanzania Locations of Important Metal Ores in Tanzania Identify locations of important metal ores in Tanzania Most metals are found naturally as compounds called minerals. Rocks are made up of crystals of metals. An ore is a rock that contains enough of a metal compounds for it to be worth extracting the metal. The most common ores contain oxides. An example is the ore haematite, which contains iron (III) oxide. Some contain other metal compounds. Malachite contains copper (II) carbonate. Tanzania is blessed with an assortment of minerals. The mineral…

TOPIC 7: CHEMICAL KINETICS, EQUILIBRIUM AND ENERGETICS The Rate of Chemical Reactions Comparison between the Rates of Chemical Reactions Compare the rates of chemical reactions Chemical reactions take place at different rates. Some are fast whereas others are very slow. Let us consider the following reactions: Addition of sodium metal to water: 2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g) The reaction takes place immediately and violently. It is therefore a fast reaction. The rusting of iron in the presence of air and water giving hydrated iron (III) oxide, F2O3.XH2O: This is an extremely slow reaction. These two reactions could be taken as representative examples…

TOPIC 6: IONIC THEORY AND ELECTROLYSIS Ionic Theory To account for the phenomena of electrolysis the Ionic Theory was put forward by Arrhenius in 1880. The theory states that electrolytes are made up of ions, which are built up in certain patterns called crystal lattice. When these substances dissolve in water, the structure is destroyed and the ions are set free to move.Concentrated mineral acids such as sulphuric acid, hydrochloric acid and nitric acid do not contain ions but they consist of molecules. However, when they are diluted, the molecular structure is destroyed and ions are formed. Electrolytes and Non-electrolytes…

TOPIC 5: VOLUMETRIC ANALYSIS Standard Volumetric Apparatus The Concept of Volumetric Analysis Explain the concept of volumetric analysis Volumetric analysis is a quantitative analysis involving the measurement of different solutions. These solutions are made to react completely and the completion of the reaction is indicated by certain substances called indicators. The quantitative composition of the solution is then determined. Important steps of volumetric analysis include: Weighing; Preparation of the solution; Titration; and Calculation In volumetric analysis, we deal with volumes of solutions. That is why this quantitative determination of solutions of substances is called volumetric analysis. The amount of a substance present…

TOPIC 4: THE MOLE CONCEPT AND RELATED CALCULATIONS The Mole as a Unit of Measurement The Mole with Other Units of Measurements Compare the mole with other units of measurements When carrying out an experiment, a chemist cannot weigh out a single atom, ion, electron, proton or molecule of a substance. These particles are simply very small. A counting unit that is useful in practical chemistry must be used. The standard unit is called one mole of the substance. One mole of each of these different substances contains the same number of the particles (atoms, molecules, ions, electrons, protons, neutrons, etc). That…

TOPIC 3: ACIDS, BASES AND SALTS Acids and Bases The Natural Sources of Acids and Bases Investigate the natural sources of acids and bases In everyday life, we deal with many substances that chemists classify as acids. For example, orange juice and grapefruit juice contain citric acid. These juices, and others of the like, contain ascorbic acid, a substance more commonly known as vitamin C. Examples of natural sources of acids and the type of acids they contain are shown in table below. Some natural sources acids SourceType of acid present Mineral acids (HCl, H2SO4, HNO3, etc.)Minerals TobaccoSalicylic acid TeaTannic…