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…
Author: Msomi Bora
Read More
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…
TOPIC 2: HARDNESS OF WATER The Concept of Hardness of Water The Concept of Hardness of Water Explain the concept of hardness of water As water flows over the land, it dissolves many mineral substances. The dissolved minerals are deposited together with water in rivers, lakes and oceans. Water is said to be hard if it contains some specific type of dissolved minerals. It is important to note that not all dissolved salts make water hard. As you learned early, water is treated in water purification plants before being piped to your home. The treatment removes only the insoluble particles…
TOPIC 1: CHEMICAL EQUATIONS A chemical equation is a representation of a chemical reaction with the help of symbols and formulas of the substances involved in the reaction. It is a chemical shorthand for representing the reacting substance or substances combining (the reactants) and the substance or substances formed as a result of the reaction (the products). Molecular Equations A Molecular equation is the one which shows the reactants combining and the products formed, in their elemental or molecular forms in a chemical reaction. An example of a molecular equation is the reaction between sodium and water to produce sodium…
TOPIC 7: FORMULA BONDING AND NOMENCLATURE Valence and Chemical Formulae The Concept of Valence Explain the concept of valence Valency is the capacity of an atom to combine with one or more atoms to form a molecule or compound. Valency also refers the number of electrons that an atom can gain, lose or share in forming a chemical bond with another atom. The valency (or combining power) depends on the number of electrons in the outermost orbit (or valency shell) involved in the formation…