Lesson 1: Introduction to Hydrocarbons PDF

Lesson 1 Introduction to Hydrocarbons  Focus Question What are hydrocarbons and how are they used?  New Vocabulary organic compound hydrocarbon saturated hydrocarbon unsaturated hydrocarbon fractional distillation cracking  Review Vocabulary microorganism: a tiny organism...

Lesson 1 Introduction to Hydrocarbons  Focus Question What are hydrocarbons and how are they used?  New Vocabulary organic compound hydrocarbon saturated hydrocarbon unsaturated hydrocarbon fractional distillation cracking  Review Vocabulary microorganism: a tiny organism, such as a bacterium or a protozoan, that cannot be seen without a microscope  Organic Compounds Chemists in the early 19th century knew living things produced a variety of carbon compounds. They called these organic compounds because they were produced by living organisms. Scientists thought that organic compounds came only from living things. Scientists thought they could not synthesize organic compounds because organisms possessed a vital force enabling them to make carbon compounds.  Disproving Vitalism Fredrich Wöhler (a German Scientist) was the first to realize that he had produced an organic compound already in the lab. The compound was UREA. A chain of similar experiments followed, and the vital force was discredited. Eventually the idea that organic compounds required a vital force was disapproved and scientist realized that they can make organic compounds in the laboratory.  Organic Compounds The term organic compound is applied to all carbon-containing compounds with the primary exceptions of carbon oxides, carbides, and carbonates, which are considered inorganic. Because there are so many carbon- containing compound, an entire branch of chemistry is devoted to this. Find the electronic configuration of Carbon.  Organic Compounds Carbon nearly always shares its electrons and forms four covalent bonds. In organic compounds, carbon atoms are bonded to hydrogen atoms or atoms of other elements near carbon in the periodic table—especially nitrogen, oxygen, sulfur, phosphorus, and the halogens.  Organic Compounds Carbon atoms also bond to other carbon atoms and form chains from two to thousands of carbon atoms in length. Because carbon forms four bonds, it forms complex, branched-chain structures, ring structures, and even cage-like structures.  Hydrocarbons The simplest organic compounds are hydrocarbons. Hydrocarbons contain only the elements carbon and hydrogen. There are thousands of hydrocarbons. The simplest hydrocarbon molecule is methane, CH4. Methane consists of a carbon atom bonded to four hydrogen atoms.  Hydrocarbons The figure below shows four different ways to represent a methane molecule. Covalent bonds are represented by a single straight line, which denotes two shared electrons. Multiple Carbon-Carbon Bonds Carbon atoms bond to each other by single, double, and triple bonds. A saturated hydrocarbon contains only single bonds. An unsaturated hydrocarbon contains at least one double or triple bond.  Refining Hydrocarbons Many hydrocarbons are obtained from the fossil fuel called petroleum. Petroleum formed from the remains of microorganisms that lived in Earth’s oceans millions of years ago. Overtime, the remains form thick layers of mud-like deposits on the ocean floor. Heat from Earth’s interior and tremendous pressure of overlying sediments transformed from this mud into oil-rich shale and natural gas. The petroleum then ran out of the shale and collected in pools that are deep in Earth’s Crust Natural gas is also formed the same time and same way as petroleum and is composed of methane with smaller amounts if other hydrocarbons that have two to five carbon atoms.  Refining Hydrocarbons Petroleum is a complex mixture of over a thousand different compounds. To be used, raw petroleum, or crude oil, is separated into simpler components or fractions. It is done by a process called Fractional Distillation, sometimes also known as Fractionation. It involves boiling the petroleum and collecting components as they condense at different temperatures.  Fractional Distillation F.D is done in fractionating tower with a temperature of near 400 degree Celsius at the bottom where the petroleum is boiling. The temperature gradually decreases towards the top. The hydrocarbons are collected as they travel up through the column and are drawn off. Lower the molecular mass, lower will the boiling point. Refining Hydrocarbons  Cracking Fractional distillation towers do not yield fractions in proportion to demand. To meet the demand, heavier fractions are converted to lighter fractions like gasoline by breaking their large molecules into smaller ones. This is called cracking. Cracking is done in the absence of oxygen and in the presence of a catalyst. Cracking also produces starting  Rating Gasoline Gasoline is not a pure substance. Rather, it is a mixture of hydrocarbons. Most molecules with single covalent bonds in gasoline have 5 to 12 carbon atoms. For the cars to consume fuel efficiently, it is important that the gasoline in the automobile engine ignite instantly and burn evenly. Straight chain hydrocarbons burn unevenly and during ignition of cars, it may cause rattling or pinging noise called knocking. Gasoline used today in cars is modified by adjusting its composition to improve performance and reduce pollution, resulting in the octane rating system. Video See Fig 8 page 663. End of Lesson  Quiz 1 Which of the following is an example of. an organic compound? A methane C water CORREC T B table salt D carbon dioxide  Quiz 2 Which of the following elements do. hydrocarbons contain? A carbon and oxygen only B carbon and hydrogen CORREC only T C carbon, hydrogen, and oxygen D nitrogen, phosphorus, oxygen, sulfur, and the halogens  Quiz 3 How is a double bond depicted in the. structural formula of a hydrocarbon? A with a single straight line B with a double straight CORREC line T C with three straight lines D with a pair of dots  Quiz 4 What is true of a saturated hydrocarbon?. A It has only single CORREC bonds. T B It has only double bonds. C It has no single bonds. D None of the above.  Quiz 5 What name best identifies the process in. which petroleum is boiled and its components are collected as they condense at different temperatures? A cracking B hydrocarbon refining C fractional CORREC distillation T D petroleum deposition