Introduction to Organic Chemistry
Chemistry tuition classes in Miracle Learning Centre is easy to understand and help you in the chemistry tuition application questions. If you do not understand chemistry in school, you must definitely come for chemistry tuition classes at Miracle Learning Centre. Let us learn about organic chemistry in this chemistry tuition lesson.
Organic chemistry is the study of carbon containing compounds. A hydrocarbon is defined as a compound that contains hydrogen and carbon only. Hydrocarbons burn completely in oxygen to produce carbon dioxide and water. This is a combustion reaction. There are many classes of organic compounds for example alkane, alkene, alcohol, carboxylic acid, esters and aromatic hydrocarbons. These compounds belong to different homologous series.
A homologous series, for example alkane, possess the same general formula. They also have similar chemical reactions, meaning they can react with similar reagents. The successive member of a homologous series differ from the next member by a CH2 group. The melting point and boiling point of a homologous series increases down the group. This is because the molecules become larger in size and the strength of the intermolecular forces also increases, hence more energy is required to overcome these forces of attraction.
Miracle Learning Centre uses a step by step approach when teaching organic chemistry. Let us take a look at alkane. The members of the alkane homologous series consists of methane, ethane, propane, butane, pentane, hexane, heptane and octane. It has the same general formula CnH2n + 2. Alkanes are generally unreactive compared to other organic compounds in other homologous series. Alkanes undergo substitution reaction under ultraviolet light. For example, methane reacts with chlorine under ultraviolet light to form chloromethane and hydrogen chloride. This is a free radical substitution reaction. Chloromethane then reacts with another molecule of chlorine to form dichloromethane and hydrogen chloride. Dichloromethane has two hydrogen atoms subsituted by chlorine atoms. Dichloromethane will be further substituted by two more chlorine atoms and the final product is tetrachloromethane. Tetrachloromethane is a common organic solvent. This takes place under ultraviolet light and is a very slow reaction.
Alkene on the other hand is a more reactive organic compound. Alkene undergoes combustion to form carbon dioxide and water. It also undergoes various addition reaction. An addition reaction is defined by a reaction in which two of the reagents combine to form a single product. Hydration is an example of addition reaction.
When ethene is added to steam (in the presence of phosphoric acid catalyst, 300 degrees celsius , 70atm), it forms ethanol. Similar propene reacts with steam to form propanol. Butene reacts with steam to form butanol.
Another example of addition is the addition of hydrogen called hydrogenation. Ethene reacts with hydrogen to form ethane, under the condition of a nickel catalyst and 200 degrees celsius. Similarly, propene reacts with hydrogen to form propane. Butene reacts with hydrogen to form butane. This is how alkene is converted to alkanes under the condition of nickel catalyst and 200 degrees celsius. Vegetable oil is converted to margarine due the this hydrogenation reaction.
The last example of addition reaction is the addition of aqueous bromine to ethene. Aqueous bromine when added to ethene forms a colorless solution when shaken. This is because an addition reaction has occured when bromine reacts with ethene to form dibromoethane. A reddish brown bromine turns colorless instantly. Hence we can tell propene reacts with bromine to form dibropropane and butene reacts with bromine to form dibromobutane.
Ethene also undergo addition polymerisation to form polyethene. This is a macromolecule made up of thousands of molecules of ethene. A common example of polyethene is our plastic bag. Other alkenes also undergo polymerisation. Propene undergoes addition polymerisation to form polypropene. Butene undergoes addition polymerisation to form polybutene.
The student at Miracle Learning Centre asks,”Why do we need to learn organic chemistry?”
Mrs Lew, a teacher at Miracle Learning Centre, explained, “Organic chemistry is used widely in daily life. Most of the things are made from hydrocarbons, the most common being plastic bags which is polyethene. Another common product is PVC, polyvinlychloride which is used as insulating material to insulate electrical wires.”
Miracle Learning Centre aims to educate students about organic chemistry. Do come to Miracle Learning Centre for more chemistry tuition lessons to learn more about organic chemistry.