In the chemical properties part, i am going to cover the chemical reactions for alkane, alkenes and alcohols. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in which all the carboncarbon bonds are single. All the carbon atoms present in an alkane are \sp3\ hybridized that is, every carbon atom forms four sigma bonds with carbon or hydrogen atoms. Free online chemical properties of alkanes practice and. Among isomeric alkanes more the branching, greater is the. Alkane molecules are nonpolar and therefore generally do not react with ionic compounds such as most laboratory acids, bases, oxidizing agents, or reducing agents. Write both structural and molecular equations for substitution reaction of methane 5.
An introduction alkanes are aliphatic hydrocarbons having onl. Physical properties the unbranched alkanes methane, ethane, propane, and butane are gases. Chemical properties of alkanes 20 m a write chemical equation for complete combustion of methane correct reactant 2m correct product 2m 4. Alkanes and cycloalkanes 11 million organic compounds which are classified into families according to structure and reactivity functional group fg. Plastic products, gasoline, natural gas alkanes are necessary for us to have these. Alkane is solid, liquid or gas at room temperature depends on the size of its molecules. Lecture 4 alkanes and cycloalkanes smart board alkane. In this context, saturated means that each carbon has the maximum number of hydrogens bonded to it. Among alkanes volatility decreases with increase in chain length. Alkenes also readily undergo halogenation a reaction in which a halogen reacts at a carbontocarbon double or triple bond to add halogen atoms to carbon atoms.
Initially, we will be concerned with the physical properties of alkanes. Apr 22, 2020 chemical properties of alkanes class 11 notes edurev is made by best teachers of class 11. Two important reactions that the alkanes do undergo are combustion and halogenation. Physical properties of alkanes comparison of boiling points for alkanes and alcohols compound b. Alkanes do not react with strong acids, bases, oxidising agents or reducing agents. When alkanes larger than ethane are halogenated, isomeric products are formed.
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. Chemical properties of alkanes part 2 class 11 video. Alkenes add hydrogen in the presence of platinum or nickel catalyst, to form alkanes. Branched alkanes normally exhibit lower boiling points than unbranched alkanes of the same carbon content. This book is licensed under a creative commons byncsa 3. Coming to the chemical properties of alkynes, we begin with their slightly acidic nature. Accordingly the acid strength of hydrogens will follow the order,alkynes alkenes alkanes. This general rule holds true for the straightchain homologs of all organic compound families. Larger molecules have greater surface areas and consequently interact more strongly. Substituted alkynes have small dipole moments due to differences in electronegativity between the triple. Chemical properties of alkynes alkynes contain a triple bond. Chemical properties of alkanes is the last part of the alkanes episodes but this marks the beginning of learning another homologous series,alkenes. Get complete study material for chemistry, class x chemistry, class xi chemistry, class xii chemistry, science, class x science covers all concepts of chemical reactions and equation, chemical reaction, chemical equations, physical changes, chemical.
Some salient physical and chemical properties of alkanes are. Alkenes have physical properties low boiling points, insoluble in water quite similar to those of their corresponding alkanes. Some addition reactions proceed through free radical mechanism. Many functional groups contain oxygen atoms, such as alcohols, ethers, aldehydes, ketones, carboxylic acids, and esters. Bromination of alkanes occurs by a similar mechanism, but is slower and more selective because a bromine atom is a less reactive hydrogen abstraction agent than a chlorine atom, as reflected by the higher bond energy of hcl than hbr. The acid dissociation constant pk a values of all alkanes are estimated to range from 50 to 70, depending on the extrapolation method, hence they are extremely weak acids that are practically inert to bases see. Hydrocarbons l 4 chemical properties of alkanes 2 chemistry class 11 neet 2020 arvind sir duration. Alkanes and alkenes physical properties and chemical. Physical properties of alkenes are quite similar to those of alkanes. Alkane names, formulas, properties memorize sections 3. However, in case of mixture of carboxylic acid salts, all probable alkanes are formed.
Properties and uses of alkanes chemistry tutorial ausetute. There are only two reactions that alkanes will undergo, both of which are free. C ch 3ch 389 ch 3oh 65 ch 3ch 2 3ch 3 36 ch 3ch 2 3oh 118 ch 3ch 2 7ch 3 151 ch 3ch 2 7oh 194 ch 3ch 2 11ch 3 235 ch 3ch 2 11oh 255 ch 3ch 2 16ch 3 316 ch 3ch 2 16oh 308 note. Alkanes are quite inert substances with highly stable nature. Alkanes are formed, on electrolysis of concentrated aqueous solution of sodium or potassium salt of saturated mono carboxylic acids. The triply bonded carbon atoms in alkynes are sp hybridized, whereas like in alkanes the single bond atoms are sp3 hybridized, causing the difference in the electronegativity. Chemical properties of alkanes part 2 class 11 video edurev. They exhibit tetrahedral geometry with a bond angle of 109. The use of hydrogenation to convert unsaturated vegetable oils to saturated fats is discussed in chapter 17 lipids, section 17. This property makes it difficult for alkanes to be converted into other types of organic molecules. It means that these properties are the function of size, shape, and branching of the molecules.
This will include reactions such as combustion, substitution, addition, hydration etc. This increase in the electronegativity of an alkyne carbon, relative to the carbon atoms in alkenes and alkanes will polarize the ch electron bond towards carbon and facilitate the release of protons. Aug 12, 2019 to identify the main chemical properties of alkanes. Hydrocarbons are molecules that consist of carbon and hydrogen only. We restore different alkanes while fractional distillation of petroleum. Within alkane structure there is free rotation about the carbontocarbon single bonds. 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. In organic chemistry, an alkane, or paraffin a historical name that also has other meanings, is an acyclic saturated hydrocarbon. Electrolysis of an acid salt gives symmetrical alkane. Free radicals, molecules with unpaired electrons, play a large role in most reactions of alkanes, such as cracking. Due to their low boiling points, lower alkanes are highly volatile. Alkane molecules are nonpolar and therefore generally do not react with ionic compounds such as most. Physical properties of alkanes chemistry assignment. Major sources of alkanes are petroleum and natural gas.
Fgs behave similarly in every molecule they are part of. Chemsketch molecular modelling activity you have learnt 7 important concepts. Neither positive ions nor negative ions are attracted to a nonpolar molecule. Alkanes formula, definition, structure, properties, videos. Feb 10, 2011 chemical properties of alkanes 20 m a write chemical equation for complete combustion of methane correct reactant 2m correct product 2m 4. Chemical properties of alkanes the main chemical property of. Physical properties, chemical properties, and uses of alkane hydrocarbons tutorial for chemistry students. For making models of alkanes, you can use toothpicks for bonds and plasticine balls for atoms. Alkanes are also called as paraffin because these compounds show very low reactivity towards most reagents. Now alkynes are slightly electronegative in nature.
Alkane names, formulas, properties memorize sections. All alkanes burn in air to give carbon dioxide and water. Chapter 2 intro to alkane conformational isomerism. Chemical properties of alkanes class 11 notes edurev. The simplest of the functional groups are the hydrocarbons, which include the alkanes, alkenes, alkynes, and aromatic hydrocarbons. Alkanes combust react rapidly with oxygen releasing energy, which makes alkanes useful as fuels. Learn the important physical and chemical properties of the alkanes. Sep, 2019 to identify the main chemical properties of alkanes.
General methods of preparation of alkanes wurtz reaction. After reading this blog post, your concepts about the physical and chemical properties of hydrocarbons will be cleared up 100%. Nothing happens when alkanes are merely mixed with oxygen o 2 at room temperature, but when a flame or spark provides the activation energy, a highly exothermic combustion reaction a chemical reaction in which a substance combines with molecular oxygen to make oxygencontaining compounds of other elements in the reaction. Like the alkanes and alkenes, alkynes of four or fewer carbon atoms tend to be gases. This document is highly rated by class 11 students and has been viewed 2643 times. Hence, it appears that wienertype indices will be the most appropriate for modeling, monitoring, and estimating these properties.
Hydrocarbons l3 chemical properties class 11 chemistry. Alkanes are made up of exclusively carbonhydrogen bonds, and single carboncarbon bonds. Alkanes and cycloalkanes bloomsburg area school district. For alkenes, alkynes and aromatic hydrocarbons, spring models can be constructed. The first three alkenes are gases, and the next fourteen are liquids. Chemistry b11 chapters 10 alkanes, alkenes, alkynes and determine in large measure the physical properties of a molecule. Chemical properties of alkanes chemistry libretexts. The reaction termed as hydrogenation, is an exothermic reaction. Methane is one of the major components of natural gas. Alkanes and alkenes physical properties and chemical properties. Igcse physical and chemical properties of hydrocarbons. Lower alkanes c 1 to c 4 are gases, middle one c 3 to c 17 are liquids and higher are solids. Alkanes are only weakly reactive with most chemical compounds.
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