Igcse physical and chemical properties of hydrocarbons. How do physical properties change in a homologous series. They are compounds that are obtained from the fossil fuel crude oil by a process called fractional. Each member of such a series shows a definite relationship in its structural formula to the members preceding and following it, and there is generally some regularity in changes in physical properties of successive members of a series. For example, you could look at boiling points of h2o, h2s, and h2se and then explain the difference with a discussion of. Variation of some physical properties in a homologous series of hydrocarbons are described below. The simplest precedent is the sequence of properties for the saturated paraffin hydrocarbons normal alkanes. Differ by ch 2 in molecular formulae from neighbouring compounds. Homologous series have the following common characteristics. Homologous series grade 11 science notes reference notes. The alkanes are a homologous series of hydrocarbons with the general. A homologous series is a family of organic compounds that. Natures chemistry homologous series national 5 chemistry. Indeed, it is common for a molecule to incorporate structural units characteristic of two or more hydrocarbon families.
The difference in the molecular weight between two consecutive homologues is 14 amu. A homologous series is a family of organic compounds which follows a regular structural pattern, in which each successive member differs in its molecular formula by a ch 2 group. Significance and properties of the homologous series. Currentvoltage characteristics of a homologous series of. This can be the length of a carbon chain, for example in the straightchained alkanes paraffins, or it could be the number of monomers in a homopolymer such as amylose. Choose from 352 different sets of homologous series flashcards on quizlet. The alcohols which only contain one hydroxyl group attached to a saturated carbon form a homologous series. A homologous series is a family of hydrocarbons with similar chemical properties who share the same general formula. They also have a similar trend in physical properties. This classification of hydrocarbons serves as an aid in associating structural features with properties but does not require that a particular substance be assigned to a single class.
Homologous series is defined as a systematic order of organic compounds having same functional group that can be represented by same general formula and prepared by same method. The general characteristics of a homologous series are. Handbook of industrial hydrocarbon processes sciencedirect. For example, alkane, alkene and alcohol are separate homologous series.
Carbon chains of varying length have been observed in organic compounds having the same general formula. Order in homologous series photograph shows the first members of various homologous series. With the increase in molecular mass in a homologous series the physical properties like melting points. In the field of organic chemistry, a homologous series is a series of compounds with the same functional group and similar chemical properties in which the. Now, experimental and computational investigations on a homologous series of. Homologous series of alkanes, alkenes and alkynes with. The homologous series of the simplest aromatic hydrocarbons begins with a compound with six carbon atoms benzene. Saturated hydrocarbons properties of saturated hydrocarbons. The series like methanol, ethanol, propanol, butanol and so on is also a homologous series. Such series are most common among organic compounds, the structural difference being a methylene group, as in the paraffin hydrocarbons. Homologous series, any of numerous groups of chemical compounds in each of which the difference between successive members is a simple structural unit. In chemistry, a homologous series is a series of compounds with the same general formula, usually varying by a single parametersuch as the length of a carbon chain. Hydrocarbons are chemical compounds that contain the elements carbon and hydrogen only.
Saturated hydrocarbons their name speaks for itself. Cbse ncert notes class 10 chemistry carbon and its compounds. In the field of organic chemistry, a homologous series is a series of compounds with the same functional group and similar chemical properties in which the members of the series can be branched or unbranched. The alkanes are a homologous series of saturated aliphatic hydrocarbons. The presented theoretical studies provide a relatively simple way to examine the adsorption systems of hydrocarbon homologous series. Saturated hydrocarbons form a homologous series of hydrocarbons. Now, experimental and computational investigations on a homologous series of a stereochemically welldefined hydrocarbon have revealed an oddeven effect in conformational behaviour in solution. This video explains the occurrence, properties of hydrocarbons along with the definition of hydrocarbon in a systematic and very attractive manner. The physical properties of various members of a homologous series change regularly with an increase in the molecular mass. In the simplest approximation, the members of a homologous series are assumed to have essentially the same properties, except for the increases in boiling point and melting point as shown in figure 41 for alkanes. By assuming the possibility of multisite occupancy adsorption we presented the theoretical expressions for adsorption isotherm and isosteric heat of adsorption.
Homologs of this series are formed when one or several hydrogen atoms attached to the benzene ring are replaced by radicals. The organisation of organic compounds into the various different homologous series makes the study of organic chemistry more systematic, orderly and effective. Homologous series is a series of compounds with similar chemical properties and same functional group differing from the successive member by ch 2. Hydrocarbons the alkanes and alkenes are examples of homologous series. No alkene has only one carbon atom in its molecule as no double bonds would be possible for the molecule called unsaturated hydrocarbons because they contain carboncarbon double bonds functional group carboncarbon double bonds. When only a little air is available, hydrocarbons burn to give carbon monoxide and carbon.
Even and oddnumbered homologues of some hydrocarbons are known to exhibit different trends in solidstate properties. Homologous series of alkanes, alkenes and alkynes with examples. Theoretical studies of hydrocarbon homologous series. Alcohols are hydrocarbon compounds containing one or more hydroxyl group o h attached to a saturated carbon atom. A homologous series is a group or family of organic compounds that has certain characteristics. A few carbon compounds also exhibit a similar pattern. Chemistry, class 11, organic chemistry some basic principles and techniques tagged with. Such series are most common among organic compounds, the structural difference being a methylene group, as in the paraffin hydrocarbons, or alkanes. Homologous series a homologous series is a group of compounds with similar characteristics and the same general formula. Homologous series is defined as a systematic order of organic compounds having same functional group that can be. The alkanes are a homologous series of aliphatic hydrocarbons. Members of the same homologous series have the same chemical properties but because they contain different number of carbon atoms their physical p.
The homologous series is a family or group of hydrocarbons or derivatives having the same functional group, same general formula and similar chemical properties. Learn homologous series with free interactive flashcards. Taking the three simplest types of hydrocarbon, alkanes, alkenes and alkynes we can write a general formula to represent the whole family or homologous series. The optical band gaps were determined by uvvis and fluorescence spectroscopy in solution. Homologous series have the same general formula with the neighbouring members of the series differing by ch 2. Some examples of homologous series are shown in the following table. Each member of the alkene homologous series differs from the next by a ch2 unit general formula of cnh2n note. Currentvoltage characteristics of a homologous series of polycyclic aromatic hydrocarbons. The functional group attached to these compounds is alcohol. A novel alkylsubstituted polycyclic aromatic hydrocarbon pah with d2h symmetry and 78 carbon atoms in the aromatic core c78 was synthesized, thereby completing a homologous series of soluble pah compounds with increasing size of the aromatic pi system 42, 60, and 78 carbon atoms. It is a complex chemical substance, whose molecules are composed of hydrogen atoms and carbon atoms. This animation also contains the expanded molecular structures of methane, ethane and butane molecules.
Members of the same homologous series have the same chemical properties but because they contain different number of carbon atoms their physical properties such as, boiling point, density, conductivity, melting point, solubility, etc differ. Chemicals in the same homologous series will show a gradual variation in one property eg. What are the characteristics of homologous series answers. A hydrocarbon homologous series is a series of hydrocarbons which.
Properties of homologous series definition, examples. A homologous series is a group of chemicals which have similar chemical properties and can be represented by a general formula. Homologous series helps in determination of structure of the successive member of the series and the property of that members can also be predicted by their series. Doc homologous series of hydrocarbons duwil genova. First three compounds are gases while compounds upto c 16 are liquids and beyond that, they assume semisolid consistency. Currentvoltage characteristics of a homologous series of polycyclic.
Homologous series chemistry, class 11, organic chemistry. The difference between two consecutive members in their composition is ch 2 unit. Homologous series of hydrocarbons online science help. Currentvoltage characteristics of a homologous series of polycyclic aromatic hydrocarbons article in chemistry 26. Homologous series homologous series characteristics. This generally will be true, except when the number of carbons is small and when the hydrocarbon chain has polar substituents. Alkanes, alkenes, alcohols, carboxylic acids and esters belong to different homologous series. Homologous series is the characteristic feature of carbon compounds in which carbon and hydrogen atoms in hydrocarbons varying by single parameter. In chemistry, a homologous series is a series of organic compounds with a similar general formula, possessing similar chemical properties due to the presence of the same functional group, and shows a gradation in physical properties as a result of increase in molecular size and mass. The chemical properties of the individual members of an homologous series are similar and they. The individual members of a homologous series are called homologs. Characteristics of homologous series of hydrocarbons all homologues of a homologous series have the same general formula e.