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Chemistry

Chemistry

AIR AND COMBUSTION

Percentage of Oxygen in Air We have read that Air consists mainly of molecules of oxygen and nitrogen with important yet trace amounts of other gases. We know that the combustion of organic material requires oxygen. The idea here is to capture a quantity of air in a measured and isolated volume and then use up all the oxygen by burning something. The remaining volume will be mostly molecular nitrogen. Equipment needed flasks water container candles rulers thermometer Procedure The volume of a flask is measured. Water is placed in a container along with a thermometer, and a flask inverted over a lit candle resting in the water. Eventually the candle goes out. Measure the height of water relative to the original water height. Calculate the volume. From the total volume, assumed to be oxygen and nitrogen, compute the percentage of oxygen.   Suppose the heights of air were measured… Read More »AIR AND COMBUSTION

Chemistry

AN ALKALI

Alkali is pronounced like alcohol, with ‘lie’ at the end instead of ‘hol’. An alkali is any substance which produces OH– ions in water. OH– ions are called hydroxide ions. If there are excess of (OH)– ions when a compound is dissolved in water, the solution is called a base or an alkaline solution. A base is generally a metal hydroxide solution.   Table below lists some of the common alkalis available in our everyday lives. Name of alkali Chemical Formula Dissociation in water Sodium Hydroxide NaOH Na+ + (OH)– Potassium Hydroxide KOH H+ + NO3– Ammonium Hydroxide NH4OH NH4+ + (OH)– A substance which will neutralize an acid, but does not dissolve in water, is called a base. For example, copper (II) oxide, iron (II) oxide and zinc carbonate are bases. They do not dissolve in water. Any base which dissolves in water is called an alkali. The outer circle encloses all bases, while the inner… Read More »AN ALKALI

Chemistry

ACIDS, BASES AND INDICATORS

WHAT IS ACIDS, BASES AND INDICATORS?   All the elements in nature fall into three classes: metals, non-metals and gases. Non-metals are also sometimes called metalloids. The compounds formed by combination of the elements can also be classified as organic and inorganic compounds. Organic compounds are formed from a combination of carbon and hydrogen; they are also sometimes known as hydrocarbons. In addition to this, all these compounds taste sour, bitter or salty. The sour tasting substances are known as acids. Bitter tasting compounds are generally soapy to feel also; they are known as bases or alkalis.   What is an acid? When a substance dissolves in water, the solution may be acidic, neutral or alkaline. An acid is any substance which produces H+ ions or H3O+ ions in water. H+ ions are called hydrogen ions; H3O+ ions are called hydroxonium ions. You will mostly see acids in reactions as forming H+ ions.… Read More »ACIDS, BASES AND INDICATORS

Chemistry

EVAPORATION AND BOILING

EVAPORATION AND BOILING (LIQUID TO GAS) On heating particles gain kinetic energy and move faster. In evaporation and boiling the highest kinetic energy molecules can ‘escape’ from the attractive forces of the other liquid particles. The particles lose any order and become completely free to form a gas or vapour. Energy is needed to overcome the attractive forces in the liquid and is taken in from the surroundings.   This means heat is taken in, so evaporation or boiling are endothermic (require heat to be added) processes. If the temperature is high enough boiling takes place. Boiling is rapid evaporation anywhere in the bulk liquid and at a fixed temperature called the boiling point and requires continuous addition of heat.   The rate of boiling is limited by the rate of heat transfer into the liquid. Evaporation takes place more slowly at any temperature between the melting point and boiling… Read More »EVAPORATION AND BOILING

Chemistry

CAREERS IN CHEMISTRY

Chemists are the people who transform the everyday materials around us into amazing things. Some chemists work on cures for cancer while others monitor the ozone protecting us from the sun. Still others discover new materials to make our homes warmer in the winter, or new textiles to be used in the latest fashions. The knowledge gained through the study of chemistry opens many career pathways. Here are just a few of the careers chosen by chemists. Agricultural Chemistry Biochemistry Chemical Education Chemical Engineering Consumer Product Chemistry Environmental Chemistry Food and Flavor Chemistry Forensic Chemistry Medicinal Chemistry   Some Career Descriptions: Biochemistry Biochemistry is the study of the structure, composition, and chemical reactions of substances in living systems. Biochemistry emerged as a separate discipline when scientists combined biology with organic, inorganic, or physical chemistry and began to study such topics as how living things obtain energy from food, the chemical… Read More »CAREERS IN CHEMISTRY

Chemistry

INTRODUCTION TO CHEMISTRY

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 relation to energy (ii) Chemistry– the study of composition of matter. Chemistry is thus defined as the branch of science that deals with the structure composition, properties and behavior of matter. Basic Chemistry involves studying:   (a) States/phases of matter Matter is anything that has weight/mass and occupies space/volume. Naturally, there are basically three states of matter. (i) Solid-e.g. soil, sand, copper metal, bucket, ice. (ii) Liquid e.g. water, Petrol, ethanol/alcohol, Mercury (liquid metal). (iii) Gas- e.g. Oxygen, Nitrogen, Water vapour. A solid is made up of particles which are very closely packed. It thus… Read More »INTRODUCTION TO CHEMISTRY

Coat of arms of Nigeria

CHEMISTRY SS 3 SCHEME OF WORK

CHEMISTRY SCHEME OF WORK FOR SS 3 CHEMISTRY SS 3- FIRST TERM 1. Petroleum or Crude Oil 2. Metals and their Compounds 3. Iron 4. Quantitative and Qualitative Analysis 5. Ethical, Legal and Social Issues   CHEMISTRY SS 3- SECOND TERM 1. Fats and Oil 2. Soap and Detergents 3. Giant Molecules (Sugars, Starch) 4. Giant Molecules (Proteins) 5. Quantitative and Qualitative Analysis   CHEMISTRY SS 3- THIRD TERM 1. Quantitative and Qualitative Analysis 2. General Revision…General Revision…General revision   Also See BIOLOGY SSS 3 SCHEME OF WORK ACCOUNTING SSS 3 SCHEME OF WORK SALESMANSHIP SSS 2 SCHEME OF WORK HISTORY SSS 2 SCHEME OF WORK DATA PROCESSING SSS 2 SCHEME OF WORK

Coat of arms of Nigeria

CHEMISTRY SSS 2 SCHEME OF WORK

CHEMISTRY SS 2- FIRST TERM 1. Periodic Table 2. Chemical Reactions 3. Mass, Volume Relationships 4. Acid-Base Reactions 5. Water. CHEMISTRY SS 2- SECOND TERM 1. Air 2. Hydrogen 3. Oxygen 4. Halogens 5. Nitrogen 6. Sulphur CHEMISTRY SS 2- THIRD TERM 1. Oxidation-Reduction (Redox) Reactions 2. Ionic Theory 3. Electrolysis 4. Hydrocarbons 5. Alkanols   Also See BIOLOGY SSS 2 SCHEME OF WORK AGRICULTURAL SCIENCE (AGRIC) SSS 2 SCHEME OF WORK ACCOUNTING SSS 2 SCHEME OF WORK SALESMANSHIP SSS 1 SCHEME OF WORK HISTORY SSS 1 SCHEME OF WORK

Coat of arms of Nigeria

SCHEME OF WORK FOR CHEMISTRY SS 1

CHEMISTRY SS 1- FIRST TERM 1. Introduction to Chemistry 2. Particulate Nature of Matter 3. Symbols, Formulae and Equations 4. Chemical Combination 5. Gas Laws CHEMISTRY SS 1- SECOND TERM 1. Gas Laws (Cont’d) 2. Standard Separation Techniques for Mixtures 3. Acids, Bases and Salts 4. Water. CHEMISTRY SS 1- THIRD TERM 1. Carbon and its Compounds 2. Chemical Industries   Also See SCHEME OF WORK FOR BIOLOGY SSS 1 SCHEME OF WORK FOR AGRICULTURE SSS 1 SCHEME OF WORK FOR ACCOUNTING SSS 1 List of Universities in USA

Chemistry

OXYGEN (O2) PROPERTIES AND USES

OXYGEN (O2) PROPERTIES AND USES   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 in compounds such as silicates, oxides, and water.   It is also dissolved in rivers, lakes, and oceans. Molecular oxygen occurs almost entirely in the atmosphere. Oxygen is highly oxidizing (a general chemical term applying to any substance, like oxygen, that accepts electrons from another substance during reaction). Oxygen reacts vigorously with combustible materials, especially in its pure state, generating heat in the reaction process.   Ozone (O3) is an allotropic form of oxygen that is more reactive than ordinary oxygen. Ozone is formed in nature by electrical discharges or… Read More »OXYGEN (O2) PROPERTIES AND USES

Chemistry

RUSTING OF IRON

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 considerable length of time, it gets covered with a red-brown flaky substance called rust. This is called rusting of iron. Conditions Necessary for the Rusting of Iron Rusting of iron (or corrosion of iron) needs both, air and water. Thus, two conditions are necessary for the rusting of iron to take place: Presence of air (or oxygen) Presence of water (or moisture) The chemical composition of rust is hydrated iron (iii) oxide, Fe2O3. xH2O   Experiment to show that Rusting of Iron Requires Both, Air and Water We take five test-tubes and put on clean… Read More »RUSTING OF IRON

Chemistry

WATER AND HYDROGEN

WATER AND HYDROGEN 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, (which is also called Heavy Hydrogen) and Tritium, T.   Preparation of Hydrogen by the Action of Metals The alkali metals, lithium, sodium, and potassium react violently with water at the ordinary temperature, yielding hydrogen. 2 Li + 2 H2O H2 + 2 LiOH Calcium reacts with water more slowly unless the water is hot, when the action is more vigorous. Ca + 2 H2O H2 + Ca(OH)2   Preparation of Hydrogen from Action of Acids Hydrogen is prepared in the laboratory by the action of acids on metals. Dilute sulphuric acid containing 1… Read More »WATER AND HYDROGEN

Chemistry

INDICATORS

INDICATORS 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. This indicator is a very good one with good color changes.   Materials Needed: Tea strainer 2 Glass quart jars with lids 1 Quart distilled water Uncooked purple cabbage Hotplate and pan   Procedure: Fill one jar with cabbage leaves that have been crushed into small pieces. Heat the distilled water to boiling, and fill the jar containing the pieces of cabbage with the hot water. Allow the jar to stand until the water cools to room temperature. Poor the cooled cabbage solution through the tea strainer into the second quart jars. Discard the… Read More »INDICATORS

Chemistry

COMPOUNDS AND FORMULA

COMPOUNDS AND FORMULA  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 a fixed composition and therefore a fixed ratio of atoms represented by a fixed formula, however the compound is made or formed.   In a compound, the elements are not easily separated by physical means, and quite often not easily by chemical means either. A compound has properties quite different from the elements it is formed from. For example, soft silvery reactive sodium + reactive green gas chlorine colourless, not very reactive crystals of sodium chloride.   Chemical word equations For any reaction, what you start with are called the reactants, and… Read More »COMPOUNDS AND FORMULA

Chemistry

SEPARATION OF MIXTURES

SEPARATION OF MIXTURES   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 of physical techniques are available to make necessary separations. All separations depend one way or other on the physical properties of substances in the mixture. The method chosen depends on. (i) The type of mixture (ii) Substance in the mixture which we are interested in.   Types of Mixtures and Separation Purity based on melting/Boiling Points Substances can be identified using their boiling and melting points Pure substances change state at a constant temperature whilst impure substances change over a range of temperature. If a solid is not pure, its melting point… Read More »SEPARATION OF MIXTURES

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