Monday, June 16, 2008

What is chemistry?
Chemistry is the study of the composition, structure, properties, and interactions of matter.


Why do we study chemistry?
We study chemistry because:
(i) Through studying chemistry, we get knowledge that enables us to solve and answer many questions that arise during our living. Chemistry helps us to answer questions like how heat is generated from burning petrol and why milk turns sour when left for some time.
(ii) Through studying chemistry, different individuals acquire different professions. For example, teachers, doctors and nurses study chemistry during their training.
(iii) The study of chemistry enables us to manufacture such items like fertilizers, paints, ink, drugs, insecticides, herbicides and dry cells all of which are used in our daily activities.
(iv) Chemistry brings pleasure to one studying it. For example, if one experimenting discovers something special, he/she feels very happy.
(v) The knowledge of chemistry is applied in other science subjects, for example biology and physics.
(vi) Chemistry enables us abandon bad beliefs like visiting witchdoctors when we are sick believing that our neighbours have bewitched us.
(vii) Chemistry enables us to take what is abundant and change it into another substance that can be used as a substitute for what is in short supply.
What is science?
Science is the knowledge obtained and tested through the use of a systematic method. The knowledge obtained through this systematic method is used to design many different things that a human being can use. The application of science in designing things that human beings use to solve their problems in their crude environment is called technology. Therefore, chemistry is a branch of science. Other branches of science are biology and physics. Being a science subject, chemistry is purely experimental and hence relies on practical work. In order to be good at chemistry, one has to study other science subjects as well.
What is technology?
Technology is the process by which human beings fashion tools and machines to increase their control and understanding of the material environment. The term is derived from the Greek words tekhnç, which refers to an art or craft, and logia, meaning an area of study; thus, technology means, literally, the study, or science, of crafting.

Name the main branches of chemistry.
The main branches of chemistry are:
(i) Organic chemistry
(ii) Inorganic chemistry
(iii) Physical chemistry
What is Organic chemistry?
Organic chemistry is a branch of chemistry in which carbon compounds and their reactions are studied. A wide variety of classes of substances—such as drugs, vitamins, plastics, natural and synthetic fibres, as well as carbohydrates, proteins, and fats—consist of organic molecules. Organic chemists determine the structures of organic molecules, study their various reactions, and develop procedures for the synthesis of organic compounds
What is Inorganic chemistry?
Inorganic chemistry is the study of the structure, properties, and reactions of the chemical elements and their compounds. Inorganic chemistry does not include the investigation of hydrocarbons—compounds composed of carbon and hydrogen that are the parent material of all other organic compounds. The study of organic compounds is called organic chemistry.
Inorganic chemists have made significant advances in understanding the minute particles that compose our world. These particles, called atoms, make up the elements, which are the building blocks of all the compounds and substances in the world around us.
What is physical chemistry?
Physical chemistry is a field of chemistry that applies the laws of physics to elucidate the properties of chemical substances and clarify the characteristics of chemical phenomena. The term physical chemistry is usually applied to the study of the physical properties of substances, such as vapour pressure, surface tension, viscosity, refractive index, density, and crystallography, as well as to the study of the classical aspects of the behaviour of chemical systems, such as thermal properties, equilibria, rates of reactions, mechanisms of reactions, and ionization phenomena.
What is the scientific method?
Scientific Method is the term denoting the principles that guide scientific research and experimentation.
What is the procedure of the scientific method; or how do we study chemistry?
We study chemistry by going through the following scientific method:
1. Identification of the problem.
A problem is an issue which needs an appropriate solution to overcome it.
E.g., the child is not happy all the time.
2. Formulation of a hypothesis
This is the formation of a tentative answer to the problem. The researcher gives a tentative answer which s/he thinks is the causative of the problem.
E.g., the child may be sick.
3. Collection of Data (Experimentation)
The third step is collecting data or information. Here the researcher seeks to get more information on the sources of the problem. In this step, the researcher would like to get evidence. In this way, many people would be involved; the eye witnesses and other persons who know something about the problem. Gathering information enlightens the researcher.
The researcher has to know where the data can be collected, the methods of collecting data and the sample to be taken.
4. Analyzing data
The researcher has to analyze data by calculating the mean, mode, median and standard deviation where possible.
5. Interpretation of Data
The data should be interpreted in a precise and concise manner to enable the reader to understand their implication. This can be done by presenting the data in graphs and charts.
6. Conclusion
Here, the researcher relates the hypothesis formulated and the data obtained after the research. After relating and evaluating, the researcher gives the conclusion.
What are physical properties of a substance?
Physical properties of a substance are properties which do not change the chemical character of the substance. Pounding, pulling, or heating, for example, do not change the chemical character of a substance. Pounded copper remains copper.
What are chemical properties of a substance?
Chemical properties are those properties characteristic of the substance when it is involved in a chemical change.
What is a physical change?
A physical change is a change which does not involve rearrangement of atoms in the substance or substances.
What is a chemical change?
A chemical change is a change of a substance in which one or more new substances with new chemical properties are formed.

What is a chemistry laboratory?

A chemistry laboratory is a special room or place where chemistry experiments are performed.
The word laboratory originates from the Latin word ‘laborare’ and it means to work hard. This means that a laboratory is a place in which people work seriously. It means that we should not make jokes in the laboratory.
What is the importance of a laboratory?
A chemistry laboratory is a special room or place where chemistry experiments are performed.
The word laboratory originates from the Latin word ‘laborare’ and it means to work hard. This means that a laboratory is a special place or room in which people work seriously. It means that the laboratory is not a place to make jokes.
Name the laboratory rules.
One of the first things a scientist learns is that working in the laboratory can be an exciting experience. But the laboratory can also be quite dangerous if proper safety rules are not followed at all times.
In the laboratory everyone is expected to adhere to rules that are laid down and this reduces the risk of accidents. The rules are as follows:
Ø Never enter the laboratory without permission from your teacher
Ø Wear a laboratory apron whenever you are working with chemicals
Ø Never perform experiments without being permitted by your teacher
Ø Never handle any equipment unless you have specific permission
Ø Never spill any chemicals in the laboratory
Ø Never eat and drink in the laboratory
Ø Never run in the laboratory
Ø Do not make noise in the laboratory
Ø Do not look directly at the apparatus being heated
Ø Read all directions for an experiment before performing an experiment
Ø When heating a test tube or bottle, point it away from yourself and others
Ø Maintain a clean work area and keep all materials away from flames
Ø Be aware of the location of the first aid kit
Ø Never smell or taste chemicals without permission
Ø Never mix chemicals for the ‘fun of it’.
Ø When diluting acids, pour acids into water and never vice versa
Ø Never use broken or chipped glassware
Ø Clean your hands thoroughly after handling chemicals
Where can we find chemistry laboratories?
A chemistry laboratory is found in places such as:
v Hospitals
v Schools
v Industries
Why is chemistry called the central science?
Chemistry is often called the central science, because its interests lie between those of physics (which focuses on single substances) and biology (which focuses on complicated life processes). A living organism is a complex chemical factory in which precisely regulated chemical reactions occur between thousands of substances. Increased understanding of the chemical behaviuor of these substances has led to new ways to treat disease and has even made it possible to change the genetic makeup of an organism. For example, chemists have produced strains of food plants that are hardier than the parent strain.
Because the field of chemistry covers such a broad range of topics, chemists usually specialize. Thus, chemistry is divided into a number of branches.
Name different methods by which mixtures can be separated:
Different methods by which mixtures can be separated are: filtration, evaporation, distillation, fractional distillation, separating funnel, recrystallization, chromatography, magnetism and sublimation.
Define the methods given above and give one example of a mixture that can be separated by the method.
Filtration is a process of separating a suspended solid, such as a precipitate, from the liquid in which it is already suspended by straining it through a porous medium (filter) that can be penetrated easily by liquids. An example of a mixture that can be separated by this method is sand and water.
Evaporation is a process of obtaining a soluble solid from its solvent. An example of a mixture that can be separated by this method is salt and water.
Distillation is the process of evaporating a liquid and condensing its vapour. An example of a mixture that can be separated by this method is alcohol and water.
Fractional distillation is the separation of a mixture into its components through differences in boiling points. An example of a mixture that can be separated by this method is ethanol and propanol (two miscible liquids).
Separating funnel method is a method used to separate two liquids with different densities. An example of a mixture that can be separated by this method is oil and water (two immiscible liquids).
Recrystallization is a method of separating a soluble solid from its impurities. An example of a mixture that can be separated by this method is impure copper sulphate.
Chromatography is a method used to separate mixtures by taking an advantage of their different rates of movement in a solvent over an absorbent material. An example of a mixture that can be separated by this method is ink.
Magnetism is a method of separating a magnetic material from a non-magnetic material. An example of a mixture that can be separated by this method is a mixture of iron filings and sulphur.
Sublimation is a method of separating a mixture that contains a substance which sublimes. An example of a mixture that can be separated by this method is a mixture of iodine and sand (iodine sublimes).
What is distillation?
Distillation is the process of heating a liquid until its more volatile constituents pass into the vapour phase, and then cooling the vapour to recover such constituents in liquid form by condensation.
What is evaporation?
Evaporation is the gradual change of a liquid into a gas without boiling.
What is condensation?
Condensation is the process of reduction of matter into a denser form, as in the liquefaction of vapour or steam.
What is the difference between distillation and evaporation?
In evaporation and in drying, the purpose usually is to obtain the less volatile constituent; the more volatile constituent is discarded.
In distillation, on the other hand, the principal object of the operation is to obtain the more volatile constituent in pure form.
The removal of water from glycerine by vaporizing the water, for example, is called evaporation, but the removal of water from alcohol by vaporizing the alcohol is called distillation, although similar apparatus is used in both cases.
What are the differences between mixtures and compounds?
The difference between a mixture and a compound are as listed in the table below:

The constituents can be separated from one another by physical methods, e.g. magnetic separation, filtration and distillation
The constituent elements cannot be separated by physical methods. Only chemical means can be used to separate them, e.g. chemical reactions
In the preparation of a mixture, there is neither chemical reaction nor change in energy
In the process of the formation of a compound, there must be a chemical reaction and change of energy occurs. The energy may be absorbed (endothermic reaction) or given out (exothermic reaction)
Mixtures may vary widely in composition
Compounds are fixed in their composition
The components retain their properties.
The constituent elements of a compound lose all chemical properties. Properties of the compound are quite different from those of the constituent elements


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