Physical properties of alkanes chemistry assignment. Learn how to recognize the alkane functional group in organic compounds. Compounds with at least one double or triple bond 2. Hydrocarbons are chain molecules of varying lengths made from hydrogen and carbon atoms only, joined together by covalent bonds.
When we discuss the chemical reactions of alkenes, we will see that the primary site of reaction is the double bond and the most common type of reaction is the addition of atoms to the double bond to make a saturated molecule. Alkanes react with halogens in a socalled free radical halogenation reaction. This change of mechanism gives rise to the opposite regiochemistry. The catalysts is not soluble in the reaction media, thus this process is referred to as a heterogenous catalysis. Covalent bonds are formed when atoms share pair of electrons. Boiling points, melting points, and densities generally increase with the size of the alkane. This is because the backbone carbon atoms in alkanes have attained their octet of electrons through forming four covalent bonds the maximum allowed number of bonds under the octet rule. This carboncarbon double bond changes the physicals properties of alkenes. Alkanes are not very reactive when compared with other chemical species. The alkanes are a homologous series of hydrocarbons. Alkenes are unsaturated form of hydrocarbons that are formed by double bonding between the carbon atoms.
Free radicals are the reactive species that participate in the reaction, which usually leads to a mixture of products. Hydrocarbons introduction alkanes isomerism preparation of alkanes physical properties of alkanes reactions of alkanes alkene introduction and isomerism preparation of alkenes physical properties of alkenes reactions of alkenes alkyne introduction, isomerism and preparation physical properties of alkynes reactions of alkynes aromatic. When alkyl halides are heated with sodium metal in the presence of dry ether, alkanes are obtained generally having double number of catoms than in alkyl halides. Physical properties of alkenes chemistry libretexts. Alkanes are chemical compounds that consist of carbon c and hydrogen h atoms, so they are also called hydrocarbons. However, ignoring financial considerations, alkanes can be prepared from. The hydrogen atoms of the alkane are progressively replaced by halogen atoms. Chapter 9 chemical and physical properties of hydrocarbons 1. The reaction is highly exothermic, and can lead to an explosion. Alkanes contain only cc and ch sigma bonds which are almost nonpolar due to very small difference of electronegativity between carbon and hydrogen atoms. Petroleum and natural gas are the major sources of aliphatic hydrocarbon while coal is an important source of aromatic hydrocarbons. The larger alkane molecules contain a higher percentage of carbon and this makes it more difficult to burn.
Ppt alkanes and alkenes powerpoint presentation free. Learn the important physical and chemical properties of the alkanes. Physical properties of hydrocarbons physical properties of. Alkane names, formulas, properties memorize sections. For molecules with the same number of carbon atoms and the. The reaction uses h2 and a precious metal catalyst. Because they use only single bonds, alkanes contain the maximum number of hydrogen atoms relative to the number of. Properties of alkanes natural gas, gasoline, oils and paraffin wax are all alkanes, and so alkanes are often used as fuels, lubricants and solvents.
Organic chemistry science at yorkdale with jessica. In this video, we continue looking at hydrocarbons. The important fuels like petrol, kerosene, coal gas, cng, lpg etc. The free radical initiators change the mechanism of addition from electrophilic addition to free radical addition. Open chain alkanes undergo free rotation about their cc bonds. Physical properties of alkanes alkanes are nonpolar only dispersion forces act between molecules. Download in free pdf hydrocarbons are composed of carbon and hydrogen. Alkenes, also known as olefins, are organic compounds that consist of carbon and hydrogen atoms with one or more carboncarbon double bonds in their chemical structure. Alkanes formula, definition, structure, properties. Conformations are the different arrangement of atoms that can be converted into one another by rotation. General methods of preparation of alkanes is the topic which has a potential of fetching a question in iit jee and jee mainadvanced examination very frequently. Realworld reading link if you have ridden in a car or a bus, you have used.
Learn the iupac system for naming alkanes and cycloalkanes. Alkanes 2 organic chemistry nowadays almost drives me mad. The simplest of the functional groups are the hydrocarbons, which include the alkanes, alkenes, alkynes, and aromatic hydrocarbons. Introduction hydrocarbon derivatives hydrocarbons are the principal compounds of crud. Scholars match the properties of six alkanes in a series of four puzzles. We look at how the viscosity, flammability and boiling points are related to the size of the. Ch08 reacns of alkenes landscape page 5 free radical addition to alkenes it is possible to obtain antimarkovnikov products when hbr is added to alkenes in the presence of free radical initiators. This reaction is known as wurtz reaction and used for the preparation of symmetrical alkanes. Fgs behave similarly in every molecule they are part of. We often refer to alkanes as aliphatic hydrocarbons, because the physi cal properties of the higher members of this class resemble those of the long carbonchain. Melting and boiling points of alkenes are similar to that of alkanes, however, isomers of cis alkenes have lower melting points than that of. Hunters class section 2 notes page 529 20002002, dr. Physical properties of alkanes organic chemistry tutorial. Explain the concentration of free radicals and how they interact with ions and charged molecules.
This section deals with wurtz reaction,frankland reaction. Chemsketch molecular modelling activity you have learnt 7 important concepts. Alkane names, formulas, properties memorize sections 3. The simplest alkene with one double bond is ethene. Alkanes and cycloalkanes bloomsburg area school district. The unbranched alkanes methane, ethane, propane, and butane are gases. Compound composed of only carbon and hydrogen saturated hydrocarbons. There is at least one such double bond in their structure. Alkanes are organic compounds that consist of singlebonded carbon and hydrogen atoms. Addition of h2 across the pbond of an alkene to give an alkane. General methods of preparation of alkanes wurtz reaction.
Alkanes are rarely prepared from other types of compounds because of economic reasons. Hunter, department of chemistry, youngstown state university section 2. The chemical structure of alkanes only consists of single bonds. Free radicals are very reactive and often go on to create more free radicals thursday, february 9, 2012. This means that they have similar chemical properties to each other and they have trends in physical properties. A free powerpoint ppt presentation displayed as a flash slide show on id. Liquid alkanes have densities less than 1gcm3 and they float on water. Compound composed of only carbon and hydrogen and single bonds. Alkenes, with double bonds, cannot undergo free rotation. At room temperatue, alkenes exist in all three phases, solid, liquids, and gases. Compound with only single bonds unsaturated hydrocarbons. Chemical properties of alkanes chemistry libretexts. Chemical and physical properties of hydrocarbons pdf.
Alkanes and cycloalkanes 11 million organic compounds which are classified into families according to structure and reactivity functional group fg. In this context, saturated means that each carbon has the maximum number of hydrogens bonded to it. Physical properties of alkanes as the number of carbon atoms in the molecules increases, they become less flammable more difficult to burn. Gcse science chemistry 91 properties of hydrocarbons. The alkanes can exist as gases, liquids, or solids at room temperature.
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