What is the homologous series?

The

homologous series applies to organic molecules or compounds that have a similar molecular formula, causing compounds to have similar chemical properties. As the molecular size of the compound increases in the homologous series, physical properties also show a gradual change. The main difference between compounds in such a series is the addition of extra carbon and dihydrogenic groups, CH2.

Many different types of compounds have a homologous range. Among the most common series are alkanes, ether and alcohols; Other homologous series include alkenes or olefins and alkynes and carboxylic acids. Alkans are compounds that contain only carbon and hydrogen associated with individual ties. Ethers are compounds that have an Ether functional group, consisting of oxygen linked to two alkanus or two aryl compounds displayed as R-O-R '. R and r 'refer to different compounds of alkanus or aryl.Ydrogen (-OH) and alkenes have a functional group of carbon pair associated with another carbon (c = c).Alkyny are similar to the Alkens, although the function group consists of a carbon molecule with a triple binding to another carbon molecule. Carboxylic acids are acids that contain at least one carboxylic group (-COOH).

The

compounds in the series will vary according to the CH2 unit and a certain molecular weight. The alkan series begins with methane, the molecular formula of the CH4 and the weight of 16.04. Another compound is ethane, with a formula C2H6 and a weight of 30.07. This is followed by butane, C4H10 formula and weight 58.12 and Pentan, formula C5H12 and weight 72.15. As you can see, Ethan contains one more carbon and two more hydrogen than methane and weighs 14 more than methane. The same occurs between ethan and butane and butane and Pentan.

The physical properties of these compounds also change as the molecules increase. Usually, as the length of the carbon chain increases, decreases the ability of the compound to dissolve in water,Although it is also dependent on the chemical nature of the functional group, because some functional groups are more soluble in water than others. As carbon chains in the homologous row extend, the boiling point of the compound changes. Although in many cases it increases, if the carbon chain begins with the forming branch, the boiling point begins to decrease. This is just one of the exceptions found in physical changes.