CHEMISTRY

MATTER

Science interprets nature in terms of energy and matter. Matter, the material of which the universe is composed, may be defined as anything that has mass and occupies space. Mass is a measure of quantity of matter. The mass of a body which is determined by means of an analytical balance is invariable, while the weight of a body is not. Weight is the gravitational force of attraction exerted by the earth on a body. The weight of a given body varies with the distance of that body from the centre of the earth. The weight of a body is directly proportional to its mass as well as the earth’s gravitational attraction. Matter exists in three physical states which are gas, liquid and solid. A gas maintains neither volume nor shape; but completely fills any container which it is introduced and may be expanded or compressed within relatively wide limits. A liquid has no fixed shape, but assumes the shape of the container only within the limit of the volume it occupies (definite volume). Volumes of liquids do not vary greatly with changes in temperature and pressure. A solid, under any ordinary condition, maintains definite volume and shape. Observed variations in the volume of solids with changes in temperature and pressure are very small. All matter can change from one state to another when heated or cooled. An example is water.   PROPERTIES OF MATTER A matter may be characterised by its intrinsic properties, i.e ., attributes that distinguish it from all other types of matter. Properties such as density, colour, physical state, melting point, hardness and electrical conductivity are known as physical properties because they can be observed without causing any change in the chemical composition of the matter. The chemical properties of matter are those that describe the chemical changes (chemical reactions) that matter undergoes. For example, the rusting of iron. Properties that are not characteristics of any particular type of matter, such as mass, length and temperature are known as extrinsic properties. A distinct portion of matter that is uniform throughout in composition and in intrinsic properties is called a phase. If a material consists of only one phase, it is said to be homogeneous matter. If it consists of more than one phase, it is classified as heterogeneous matter. Iron, copper, salt and a solution of salt in water are examples of homogeneous matter, while wood, granite, concrete, and a mixture of ice and water are examples of heterogeneous matter, while wood granite, concrete, and a mixture of ice and water are examples of heterogeneous matter. The phases of heterogeneous matter have distinct boundaries and are usually easily discernible. In graphite, for example, it is possible to identify pink feldspar crystals, colourless quartz crystals and shiny black mica crystals. Thus, graphite is said to consist of three phases. A mixture may be homogeneous or heterogeneous. Homogeneous mixtures are called solution and the single phase in which a solution occurs may be gaseous, liquid or solid. A solution is made up of more than one substance, one being uniformly dispersed in the other. Each phase of a heterogeneous mixture has its own properties. A homogeneous mixture has a single set of intrinsic properties, but each of these properties depends on the composition of the mixture. The density, taste, boiling point and electrical conductivity, for example, of aqueous salts solutions vary with the proportions of salt and water present. Pure substances are homogeneous materials that have fixed compositions and invariable intrinsic properties. There are two types of pure substance namely: An element: This is a pure substances that cannot be decomposed into any simpler pure substance. A compound: This is a pure substance that is composed of two elements in a fixed and definite proportion. The preparation of a compound from the constituent element is known as synthesis, while element is called analysis.

Posted in CHEMISTRY | Tagged , , | Leave a comment

INTRODUCTION TO CHEMISTRY

Chemistry may be defined as the science that is concerned with the composition and the structure of matter, and with the forces that hold the structures together. Chemistry as a science has, as its primary objectives, the determination of the nature and properties of the non-living matter, which surrounds us, and the preparation of new substances that are scientifically interesting, or generally useful from the materials which nature has provided. In trying to determine the nature of substances, it probes into principles governing the changes that matter undergoes, when subjected to conditions which they normally do not encounter, such as high temperature, high pressure, contact with other materials under different conditions, etc. The focus of chemistry, however, is probably on the chemical reaction. The interest of chemistry extends to every conceivable aspect of these transformations engendered by chemical reactions, and includes such considerations as – detailed descriptions of how and at what rate, reactions proceed, the conditions required to bring about desired changes, and to prevent undesired changes, the synthesis of substances that occur in nature and those that have no natural counterparts and the quantitative mass relations between the materials involved in chemical changes. The three main branches of chemistry are: physical, inorganic and organic. There are in addition, other branches, such as biochemistry which deals with the effects of chemicals on living cells, medicinal chemistry which deals with the physiologically active compounds such as aspirin, chloroquine and so on, industrial chemistry, which considers the applications of chemistry in industries and environmental chemistry which investigates the possible adverse effects of chemistry on the environment. The study of chemistry helps us acquire knowledge about matter. Being an experimental science, we perform experiments, learn to observe, record and make intelligent inferences. Chemistry has contributed greatly towards providing our basic needs and improving the quality of our life. Lastly, the study of Chemistry is designed to introduce learners to the basic ideas of the subject, how these ideas help to explain the materials in our world, and how they can be changed.   CHEMISTRY IN OUR LIFE  There are lots of chemical changes around us all the time. These include: Cooking. Lighting a match. Burning fire wood. Rusting nails. Rotten leaves. Making of palm. Manufacturing of drugs, etc.   All the things we use every day such as: Soaps and detergents. Hair cream and perfumes. Oil and margarine. Plastics made through chemical processes.   SCIENTIFIC METHOD Chemistry, and other fields of science, have developed through a series of discoveries. They use their senses to observe what is happening around them. Through observation, they see a certain pattern which often leads to a problem they try to solve. They put forward a reasonable explanation called hypothesis and carry out appropriate experiments to test it. They then carefully record their observations and the results of their experiments. If the experiments support the hypothesis, they carry out further investigations. When a hypothesis has been tested and found to be correct within the limits of available evidence, it becomes a theory. A scientific law or principle is established only after the theory has been extensively tested and proven true without any exception. If the experiments give negative results, then the scientist goes back to his or her hypothesis and either modifies it or puts forward a new hypothesis. This way of studying a problem is known as the scientific method and it is the foundation of all scientific research.   USES OF CHEMISTRY The study or knowledge of Chemistry has contributed greatly towards providing our basic needs and improving the quality of our life. These include: FOOD: The use of fertilisers, insecticides and pesticides has helped to increase food production. Chemical processes are designed to preserve and store food for a long period of time; so that it can be exported and made available to more people. CLOTHING: Through intensive chemical research, manmade textile fibres are produced. These have made available, a wide range of clothing materials for man’s use. MILITARY: The duty of the military is to defend the territorial integrity of a nation or state. The military cannot do this without ammunition. Chemistry has contributed to the discovery and description of the behaviour of chemical substances such as explosives used by the military. The gunpowder used by the earliest guns was made by mixing sulphur, charcoal and potassium trioxonitrates (V). SPACE SCIENCE: In our efforts to gain more knowledge of the other planets and outer space around us, special rockets called space-rockets are sent into space. The first space rocket was sent into space on October 4, 1957 by Russia. In July, 1969, Apolio II Astronauts Neil Armstrong and Edwin Aldrin landed on the moon. These were made possible by science and technology. HOUSING: To overcome the present need for housing and maximise use of land space especially in cities, many high-rise buildings are being constructed. These buildings need materials like cement, concrete, steel, bricks and tiles which are produced by chemical industries. MEDICINE: Health is wealth. The health life that many people enjoy is due to the variety of medicines that are available as a result of chemical research and technology. TRANSPORTATION: Modern transportation system is an essential feature of today’s world. This rapid development from carts pulled by animals to the latest air craft was made possible by chemicals producing suitable fuels and structural materials like alloys, which are light, strong and heat resistant.   ADVERSE EFFECTS OF CHEMISTRY Chemical processes and products also have negative or adverse effects on our daily life. These include:- 1) Corrosion of Iron Corrosion or rusting of iron occurs when iron is exposed to water and air (oxygen). Corrosion can be regarded as the slow deterioration of iron to iron (III) oxide: Rusting can be prevented by: Application of protective coating. Application of sacrificial metal. Cathodic protection. Alloying. Galvanising. Oiling and greasing.   2) Pollution One of the main adverse effects of chemical industries is the pollution of our as environment by: Chemical wastes from factories and oil refineries. Radioactive wastes from nuclear plants. Oil spillage, exhaust from motor vehicles. Pesticides, fertilisers and acid rain have made our environments unclean and endangered plants and animals life. Human health is also threatened by environmental pollution.   3) Drug Abuse Drug abuse and drug addiction is a major problem in our society, especially among the youth. Drugs that are abuse are heroin, cocaine and morphine. These drugs are not used for medical treatment, rather they are additive and some bad people in the society produce and sell them to make huge profit. Many countries have imposed strict laws to control pollution and drug abuse; but the most effective control measure is education.   CAREERS USING CHEMISTRY Have you thought of what you want to do when you leave school? Chemistry opens door to many careers. It is sometimes called ‘the central science’, because it lies between Biology and Physics. So if you would like to study these further, Chemistry is a great help. But hopefully you will want to learn more about Chemistry because you enjoy it! Here are some careers where further studies in Chemistry will be an advantage, if not a requirement: Agricultural Scientist. Animal technician. Art restorer. Bacteriologist. Biochemist. Brewer. Chemical engineer. Chemist. Civil engineer. Civil Service Science Officer. Conservationist. Cosmetics scientist. Dental technician. Dentist. Doctor. Electrical engineer. Environmental Health Officer. Food scientist. Forensic scientist. Geologist. Horticulturalist. Information Scientist. Journalist (science). Laboratory technician. Lecturer in science. Manager in an industry. Marine scientist. Marketing. Materials Scientist. Medical technician. Metallurgist. Patent lawyer. Pathologist. Personnel manager. Pharmacist. Photographer. Pollution controller. Production manager. Quality controller. Research Scientist. Safety officer. Sales person. Scientific archaeologist. Sports Scientist. Teacher of science. Technical support staff. Technical writer. Veterinary surgeon/assistant. Waste disposal manager/scientist Water technologist Wine taster Zoologist.

Posted in CHEMISTRY | Tagged , , | Leave a comment

ETHICAL, LEGAL AND SOCIAL ISSUES IN CHEMISTRY

The study of chemistry has brought tremendous, positive development to the world and to Nigeria in particular. Chemistry has contributed greatly towards providing our basic needs and improving the quality of our life. For example, the provision of clothing, housing, better food and transportation is made possible through the knowledge of chemistry. However, there are some products of science (chemical wastes) that can cause havoc to the lives of plants and animals and the environment.   WRONG APPLICATIONS OF SCIENCE (CHEMISTRY)  Chemistry can be applied in a right way to bring about advantages and comfort to people. On the other hand, wrong application of chemistry in the area of chemical waste management results in adverse effect of environmental pollution, health hazards and eventual death.   IMPLICATIONS OF WRONG APPLICATION OF CHEMISTRY Pollution: Wrong application of chemistry has led to the contamination of the environment, especially water and air, with harmful substances that threaten both plants and animals. nor Drug Abuse: The knowledge of chemistry has provided drugs like heroin, cocaine and morphine which have had adverse effects on so many lives that use them. Abortion: When science is wrongly applied, abortion, which is a risky exercise, may result to death. War: Scientific practice (chemical processes) has led to the production of weapons of destruction. For example, guns, gun powder, and nuclear bombs are chemical products used during wars and by criminals to make life miserable for citizens. Mercy Killing: Some chemical products have been used to kill patients with terminal disease without allowing natural death to take its course. This is called mercy killing or euthanasia.   ROLE OF GOVERNMENTS IN PREVENTING CHEMICAL DEGRADATION The government of every country has a vital role to play in preventing chemical degradation. These roles include: Legislation – the government should enact a law that will curtail indiscriminate disposal of chemical wastes, pollutants manufacture and sale of illicit drugs and other illegal chemical products. Establish regulatory bodies to ensure and enforce the law. Setting a minimum standard for the establishment of chemical industries. Government should ensure the proper and effective enforcement of the standards and legislation. Organising public enlightenment campaigns for all citizens on the adverse reactions of some chemical products and wastes i.e. to educate the citizens.

Posted in CHEMISTRY | Tagged , , | Leave a comment

 

gre助考 gre在家代考 gre替考 gre网上代考 gre网考代考 gre网考作弊 gre远程代考 gre代考价格 gre代考多少钱 gre代考被抓 gre代考靠谱吗 机构Mexm.net

error: Content is protected !!