The alkanes are a homologous series of hydrocarbons. Alkanes have simple carbon bonds, low melting and boiling points as well as low viscosity. Alkanes are very stable because the ch and cc double bonds are relatively stable and difficult to break. The reaction occurs at a convenient rate only in the presence of. In fact, the alkanes undergo so few reactions that they are sometimes called paraffins, from the latin parum affinis, meaning little affinity. Physical properties of alkanes chemistry libretexts. Because alkanes have relatively predictable physical properties and undergo relatively few chemical reactions other than combustion, they serve as a basis of. Aug 31, 2018 alkanes are used to prepare black carbon, water gas, alkyl halides, alcohols, and aldehydes, they are homologous series as each compound exceeds the previous one by ch 2 group, they have a general molecular formula, the same chemical properties and graduated in physical properties, liquid and gaseous alkanes are used as fuel. They are only composed of carbon and hydrogen no other molecule. 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.
Halogens, especially chlorine and bromine add on alkenes readily producing a dihalogen derivatives. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in which all the carboncarbon bonds are single. Properties of alkanes alkanes are the simplest organic molecules, consisting of only carbon and hydrogen and with only single bonds between carbon atoms. Alkanes are not very reactive and have little biological activity. 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. Major sources of alkanes are petroleum and natural gas. The use of hydrogenation to convert unsaturated vegetable oils to saturated fats is discussed in chapter 17 lipids, section 17. Almost all of the chemical reactions of alkene occur at the double bond. The properties of alkynes pretty much follow the same pattern of those of alkanes and alkenes. This is because carboncarbon cc and carbon hydrogen ch bonds are quite strong since carbon and hydrogen atoms have nearly the same electronegativity values. Alkenes are a family of compounds containing hydrogen and carbon only hydrocarbons with a carboncarbon double bond.
Among alkanes volatility decreases with increase in chain length. Furthermore they have low density and are waterinsoluable. Alkanes are immiscible in water but freely miscible. Physical properties of alkanes chemistry assignment. Today we are going to cover all chemical properties of alkanes in this video. The molecules that have a lower molecular weight are gases at room temperature and as the molecular weight increases their physical state changes from gas to liquid and then to solids. Branched alkanes normally exhibit lower boiling points than unbranched alkanes of the same carbon content.
Physical properties of alkanes organic chemistry tutorial. Molecular modeling of the physical properties of alkanes. Properties of alkanes alkanes are organic compounds that consist entirely of singlebonded carbon and hydrogen atoms and lack any other functional groups. Alkane molecules are nonpolar and therefore generally do not react with ionic compounds such as most laboratory acids, bases, oxidizing agents, or reducing agents. Lower alkanes c 1 to c 4 are gases, middle one c 3 to c 17 are liquids and higher are solids. Chemical properties of alkenes chemistry assignment. Also, i am going to give you a clear idea by comparing the the physical properties of alkenes, alkanes and alcohols versus each other. The unbranched alkanes methane, ethane, propane, and butane are gases. Since there is very little difference between the electronegativities of carbon and hydrogen, alkanes are almost nonpolar.
Sep 28, 2019 we are doing hydrocarbon of organic chemistry. Therefore, it is very difficult to break their bonds, unless they are heated to fairly high temperatures. Alkenes react with a much richer variety of compounds than alkanes. Alkynes have stronger force of attraction than alkanes or alkenes. Properties and uses of alkanes chemistry tutorial ausetute. The first four members of straight chain alkanes methane, ethane, propane and butane are gases. Difference between alkanes and alkenes compare the.
Two important reactions that the alkanes do undergo are combustion and halogenation. It deals with their formulae and isomerism, their physical properties, and an introduction to their chemical reactivity. The characteristic reaction of alkanes is substitution. The physical properties of alkenes and alkynes are generally similar to those of alkanes or cycloalkanes with equal numbers of carbon atoms. Alkynes resemble the alkenes and alkanes in physical properties. May 15, 2020 to identify the main chemical properties of alkanes.
Alkanes vary with the molecular weight and the molecular structure. Alkanes are quite inert substances with highly stable nature. Physical properties of alkane carbon compound youtube. Volatility refers to the ability of a liquid to change into vapour state. Chemical properties of alkanes chemistry libretexts. In the alkane family, each member differs from a previous member only by having an additional ch 2 unit. Physical and chemical properties of alkanes slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. This means that they have similar chemical properties to each other and they have trends in physical properties. Methane is one of the major components of natural gas. By the time you get 17 carbons into an alkane, there are unbelievable numbers of isomers. Journal of chemical information and computer sciences 1996, 36 6, 10921097. In organic chemistry, an alkane, or paraffin a historical name that also has other meanings, is an acyclic saturated hydrocarbon.
Chemical properties of alkanes what are examples of. Many functional groups contain oxygen atoms, such as alcohols, ethers, aldehydes, ketones, carboxylic acids, and esters. Hence, the members of the alkane family have closely related properties which vary in a systematic and predictable way. It is because of this relative inertness that alkanes are also called paraffins. Physical properties of alkanes are consistent with their chemical structure. The physical properties of alkynes are very similar to those of the alkenes. Alkenes contain a carboncarbon double bond which changes the physical properties of alkenes.
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. Alkynes have a higher melting point than the alkanes and alkenes. The alkanes from pentane through to c 16 are liquids with the remainder larger molecules being solids. Apart from the following three reactions, alkanes can hardly carry out other reactions. We restore different alkanes while fractional distillation of petroleum. Alkanes are not very reactive when compared with other chemical species. The simplest of the functional groups are the hydrocarbons, which include the alkanes, alkenes, alkynes, and aromatic hydrocarbons. Oct 25, 2014 alkanes and alkenes do not react as follows. Chemical properties of alkane carbon compound duration. Chemical properties of alkenes linkedin slideshare. Alkanes are used to prepare black carbon, water gas, alkyl halides, alcohols, and aldehydes, they are homologous series as each compound exceeds the previous one by ch 2 group, they have a general molecular formula, the same chemical properties and graduated in physical properties, liquid and gaseous alkanes are used as fuel.
Physical properties of alkenes are quite similar to those of alkanes. The first three alkenes are gases, and the next fourteen are liquids. Definition and applications to the prediction of physical properties of alkanes. Igcse physical and chemical properties of hydrocarbons. The product is an alkane having the same carbon skeleton as the alkene. Chemical properties of alkane carbon compound youtube. The alkanes range in complexity from the simplest case of methane. Alkanes formula, definition, structure, properties, videos. Neither positive ions nor negative ions are attracted to a nonpolar molecule. All alkanes can be burned, and the reaction exothermic. Since these bonds are quite strong, alkanes are the least reactive of all the hydrocarbons.
Alkenes on the other hand have carbondouble bondstwo carbon d. This because alkenes are unsaturated hydrocarbons that have a double bond, cc, between two carbon atom. Hydrocarbons chemical properties of alkanes organic. All liquid alkanes are less dense than water and therefore float on it. Since alkanes consist exclusively of carbon and hydrogen held together by single. Alkynes are unsaturated carbon that shares a triple bond at the carbon site. Alkanes, c412 c5h14 cid 94630 structure, chemical names, physical and chemical properties, classification, patents, literature, biological activities, safety. Due to very little difference of electronegativity between carbon and hydrogen and covalent nature of cc bond or ch bond, alkanes are generally nonpolar molecules. Identify the physical properties of alkanes and describe trends in these properties.
Solubility in nonpolar solvents, such as ether and acetone, is extensive. Alkenes react with a much more compound variety than alkanes. Using standard conditions 25 o c, 1atm, alkanes up to 4 carbons i. All the carbons are sp 3 hybridized, having 4 single bonds to either carbon or hydrogen. Alkanes are also called as paraffin because these compounds show very low reactivity towards most reagents. Jan 26, 2016 alkanes have simple carbon bonds, low melting and boiling points as well as low viscosity. All alkynes are odourless and colourless with the exception of ethylene which has a slight distinctive odour.
Some important chemical reactions of alkanes are discussed below. Alkanes are less dense than water alkanes float on top of water. Hydrogenation is used in the manufacture of margarine from vegetable oils. Alkanes are nonpolar molecules so they are more soluble in nonpolar solvents than they are in polar solvents. There are two main molecular arrangements in alkanes. If you continue browsing the site, you agree to the use of cookies on this website. Physical properties the unbranched alkanes methane, ethane, propane, and butane are gases. What are the physical and chemical properties of hydrocarbons.
Properties and uses of alkanes chemistry tutorial key concepts. The viscosity of liquid alkanes increases as the number of carbon atoms increase. Alkynes have higher boiling points than alkanes or alkenes, because the electric field of an alkyne, with its increased number of weakly held. Among isomeric alkanes more the branching, greater is the. Physical properties, chemical properties, and uses of alkane hydrocarbons tutorial for chemistry students. The ultimate products of this reaction are alkanes. Chemical properties of alkanes what are examples of alkanes.
Due to their low boiling points, lower alkanes are highly volatile. Alkanes have low melting or boiling points because of the very weak intermolecular forces between alkane molecules. Journal of chemical information and computer sciences 1996, 36 4, 844849. What are the differences in chemical properties between. Jun 15, 2017 the data in table shows the physical properties of the first ten straightchain alkanes. Because alkanes have relatively predictable physical properties and undergo relatively few chemical reactions other than combustion, they serve as a basis of comparison for the properties of many other organic compound families. Oct 07, 2014 it gives the description of chemical and physical properties of alkanes. From the physical properties of the alkanes, it can be established that. Hydrogenation is the addition of molecular hydrogen h 2 to a multiple bond, which converts alkenes to alkanes. Boiling points, melting points, and densities generally increase with the size of the alkane.