(a) Physical properties Hydrogen is a neutral, colourless and odourless gas. When mixed with air it has a characteristic pungent choking smell It is insoluble in water thus can be collected over water. It is the lightest known gas. It can be transferred by inverting one gas jar over another. (b) Chemical properties. (i) […]
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Occurrence Hydrogen does not occur free in nature. It occurs as Water and in Petroleum. School laboratory Preparation Procedure Put Zinc granules in a round/flat/conical flask. Add dilute sulphuric(VI) /Hydrochloric acid. Add about 3cm3 of copper(II)sulphate(VI) solution. Collect the gas produced over water as in the set up below. Discard the first gas jar. Collect several
REACTION OF METALS WITH WATER The higher the metal in the reactivity series the more reactive the metal with water. The following experiments show the reaction of metals with cold water and water vapour/steam. (a) Reaction of sodium/ potassium with cold water: Procedure Put about 500cm3 of water in a beaker. Add three drops of
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WATER POLLUTION Water pollution take place when undesirable substances are added into the water. Sources of water pollution include: (i) Industrial chemicals being disposed into water bodies like rivers, lakes and oceans. (ii) Discharging untreated /raw sewage into water bodies. (iii) Leaching of insecticides/herbicides form agricultural activities into water bodies. (iv) Discharging non-biodegradable detergents after
WATER Pure water is a colourless, odourless, tasteless, neutral liquid. Pure water does not exist in nature but naturally in varying degree of purity. The main sources of water include rain, springs, borehole, lakes, seas and oceans: Water is generally used for the following purposes: (i) Drinking by animals and plants. (ii) Washing clothes. (iii)
REACTIVITY SERIES OF METALS/ELEMENTS Metals compete for combined Oxygen. A metal/element with higher affinity for oxygen removes Oxygen from a metal lower in the reactivity series/less affinity for Oxygen. When a metal/element gains/acquire Oxygen, the process is called Oxidation. When metal/element donate/lose Oxygen, the process is called Reduction. An element/metal/compound that undergoes Oxidation is
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The following experiments show the reaction of non-metals with Oxygen and air. Burning Carbon Procedure (a) Using a pair of tongs hold a dry piece of charcoal on a Bunsen flame. Observe. Place the products in a beaker containing about 2cm3of water. Test the solution/mixture using litmus papers (b) Using a pair of tongs hold
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Oxygen is put in cylinders for use where natural supply is not sufficiently enough. This is mainly in: (i) Mountain climbing/Mountaineering-at high altitudes, the concentration of air/oxygen is low. Mountain climbers must therefore carry their own supply of oxygen for breathing. (ii) Deep sea diving-Deep sea divers carry their own supply of Oxygen. (iii) Saving
The following experiments show the reaction of metals with Oxygen and air. Burning Magnesium Procedure (a) Cut a 2cm length piece of magnesium ribbon. Using a pair of tongs introduce it to a Bunsen flame. Remove it when it catches fire. Observe. Place the products in a beaker containing about 5cm3 of water. Test the solution/mixture
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OXYGEN a) Occurrence. Fifty 50% of the earth’s crust consist of Oxygen combined with other elements e.g. oxides of metals About 70% of the earth is water made up of Hydrogen and Oxygen. About 20% by volume of the atmospheric gases is Oxygen that form the active part of air. b) School laboratory preparation
THE ATMOSPHERE The atmosphere is made up of air. Air is a mixture of colourless, odourless gases which is felt as wind (air in motion). All living things breathe in air for respiration. Plants use air for respiration and photosynthesis. The main gases present in the atmosphere/air The following experiments below shows the presence and
. In a school laboratory: (i) An acid may be defined as a substance that turns litmus red. (ii) A base may be defined as a substance that turns litmus blue. Litmus is lichen found mainly in West Africa. It changes its colour depending on whether the solution is in basic/alkaline or acidic. It is
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(A) PHYSICAL PROPERTIES OF ACIDS Acids have a characteristic sour taste Most acids are colourless liquids Mineral acids are odourless. Organic acids have characteristic smell All acids have pH less than 7 All acids turn blue litmus paper red, methyl orange red and phenolphthalein colourless. All acids dissolve in water to form an acidic solution.
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A physical/temporary change is one which no new substance is formed and is reversible back to original. A chemical/permanent change is one which a new substance is formed and is irreversible back to original. The following experiments illustrates physical and chemical changes (a) Heating ice Place about 10g of pure ice in a beaker.
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METHODS OF SEPARATING MIXTURES Mixtures can be separated from applying the following methods: (A) DECANTATION Sediments can be separated from a liquid by pouring out the liquid. This process is called decantation. Experiment Put some sand in a beaker. Add about 200cm3 of water. Allow sand to settle. Pour off water carefully into another beaker.
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CLASSIFICATION OF SUBSTANCES Substances are either pure or impure. A pure substance is one which contains only one substance. An impure substance is one which contains two or more substances. A pure substance is made up of a pure solid, pure liquid or pure gas. A mixture is a combination of two or more pure
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(a) Chemistry is used in the following: (i) Washing/cleaning with soap: Washing/cleaning is a chemical process that involves interaction of water, soap and dirt so as to remove the dirt from a garment. (ii) Understanding chemicals of life Living thing grow, respire and feed. The formation and growth of cells involve chemical processes in living
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CHEMISTRY LABORATORY AND APPARATUS Chemistry is studied mainly in a science room called a school chemistry laboratory. The room is better ventilated than normal classroom. It has electricity, gas and water taps. A school chemistry laboratory has a qualified professional whose called Laboratory technician/assistant. All students user in a school chemistry laboratory must consult the
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WATER ON EARTH Water is an important item in our universe. We need water for transport (lakes and oceans), Generation of power, (hydroelectricity), drinking industrial processes, manufacturing and cooling among others. Very little of the world’s water is fresh (2.6%). Most of it (97.4%) is in oceans. Most of the fresh water is frozen (76%).
INTRODUCTION TO CHEMISTRY Chemistry is a branch of Science. Science is basically the study of living and non-living things. The branch of science that study living things is called Biology. The branch of science that study non-living things is called Physical Science. Physical Science is made up of: (i) Physics– the study of matter in
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