Organic Chemistry,Alkanes, Alkenesfashion Done by Ang An JunClass: 4P201 Hwa Chong Institution |
Lesson 1: What are we studying?Monday, August 16, 2010Organic Chemistry
There are millions of organic compound because the carbon atom has 4 electrons in the outer shell and therefore to achieve a stable octet structure, it forms 4 covalent bonds with
Ability of carbon to combine with other atoms of its own kind is the special characteristic of the carbon atom. 8:14 AMLesson 2: Where are organic compounds from!?Lesson 2: Where do organic compounds come from? Main sources of organic compounds is crude oil or petroleum Crude oil is a mixture of many different organic compounds, a large number of them belonging to a group of hydrocarbons called alkanes. A hydrocarbon is a compound containing only carbon and hydrogen.
8:09 AMLesson 3: Homo WHAT!?Lesson 3: Homo what? Because of the large number of organic compounds, they can be divided into groups having the same general formula and related structures and properties, which is also called a homologous series. A homologous series is a family or organic compounds with similar chemical properties. Characteristics of homologous series · Members have the same general formula -Each member of the series differs from the next by a –CH2– unit. · Members have similar structures -They have the same functional group -Functional group is an atom or a group of atoms that gives the characteristic properties to a molecule. · Members can be made by similar methods · Members have similar chemical properties but varying in reactivity. · Physical properties vary gradually along the series -Melting and boiling points increase gradually as the no. of carbon atoms in the molecule increases -Viscosity increases as relative molecular mass and size increases. 7:42 AMLesson 4: Fuels!Lesson 4: Fuels! The main sources of fuels are 1) Natural gas -Found together with crude oil trapped under pressure in vast deposits below the sea-bed -About 95% in methane (CH4) with small amounts of H2, N2, CO, CO2, H2S
-Carried in pipes and used in homes for cooking and heating or it can be liquefied and transported as liquefied natural gas (LNG) in large tanker. 2) Petroleum -Petroleum is a black viscous liquid. A complex mixture of hydrocarbons with small amounts of sulfur-, nitrogen-, and oxygen- containing compounds present as impurities. In this form, petroleum is of little use because it has to be refined to make useful fuels and chemicals. -In oil refining, the separation of petroleum into useful fractions is achieved by fractional distillation. This is because the hydrocarbons have different boiling points. - Fractional distillation of petroleum · In the fractional column, both condensation and vaporization occurs. · As vapour rises up the column, the vapours condense and are collected in the trays. · More hot vapours enter the column and causes the liquid in the tray to further vapourise and rise up the volumn. · Repeated cycles of condensation and vaporization will push the vapours of the volatile liquids higher up the column. · Results in the separation of the mixture of vapours so that different fractions are collected at different heights of the column. - Some fractions obtained by fractional distillation are more useful than others, therefore chemists have developed ways to convert the large hydrocarbon molecules in the heavy fractions to small lighter molecules, through cracking, the long-chain hydrocarbons in the heavier fractions are smaller molecules in the petrol, kerosene or diesel fraction. Cracking is the process of breaking down larger hydrocarbon molecules into smaller molecules. Ø Conditions for catalytic cracking Ø Catalyst e.g. finely powdered aluminium oxide and silicon (IV) oxide Ø High temperature Ø High pressure
7:31 AMObjectivesQuizIntroduction of organic chem! » Quiz Maker Videostag |
