Chemistry

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: An acid may be defined as a substance that turns litmus red. 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 thus able to

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. Most

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 Heating ice Place about 10g of pure ice in a beaker. Determine its

Mixtures can be separated from applying the following methods: 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. Observation Sand settles at the

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 substances which can

Chemistry is used in the following: 1. 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. 2. Understanding chemicals of life Living thing grow, respire and feed. The formation and growth of cells involve chemical processes in living things

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 Laboratory technician/assistant for all

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%). Only a tiny

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: Physics- the study of matter in relation to energy Chemistry–

Oxygen (O2) is an active, life-sustaining component of the atmosphere; making up 20% by volume of the air we breathe. It is colorless, odorless and tasteless. Oxygen is the most widely occurring element on earth. Because it forms compounds with virtually all chemical elements except the noble gases, most oxygen is bound with other elements

Corrosion The eating up of metals by the action of air and moisture on their surface is called corrosion. The corrosion of iron is called rusting. While other metals are said to ‘corrode’, iron metal is said to ‘rust’. Rusting of Iron When an iron object is left in damp air (or water) for a

Hydrogen is the simplest element. It is the first element in the periodic table, and it is placed in Group I of the periodic table.   Hydrogen Occurrence Hydrogen is the lightest element and the most abundant element in the universe. Hydrogen occurs naturally as a mixture of the three isotopes: Protium, H, Deuterium, D,

Red cabbage juice solution works well instead of universal indicator solution.   Making Cabbage Indicator Acid base indicators are chemicals that change colour in the presence of different pH levels. These are usually larger organic molecules. Some, like that in purple cabbage, are natural. You will be making an acid base indicator from purple cabbage.

A compound is a pure substance formed by chemically combining at least two different elements. Compounds are two or more different elements combined. Their atoms have been joined or bonded together.   Compounds can be represented by a FORMULA. There must be at least two different types of atom (elements) in a compound. Compounds have

Sometimes we need pure substances as opposed to impure ones. You can imagine a mixture of sand and table salt and imagine how much use you would have for it. or imagine the manufacture of drugs and medicines. Purity is highly essential here as it is crucial to our well-being and health.   A range