Alkanes essential characteristic

Alkanes have the general formula C H2 +2, where n = 1, 2,. The essential characteristic of alkane hydrocarbon molecules is that only single covalent bonds are present. The alkanes are known as saturated hydrocarbons because they contain the maximum number of hydrogen atoms that can bond with the number of carbon atoms present. 

The lowercase n in Reaction 2.14 represents a large, unspecified number. From this reaction, we see that polyethylene is essentially a very long chain alkane. As a result, it has the chemical inertness of alkanes, a characteristic that makes polyethylene suitable for food storage containers, garbage bags, eating utensils, laboratory apparatus, and hospital equipment... 

Most alkenes contain not only the carbon-carbon double bond but also alkyl groups, which have essentially the alkane structure. Besides the addition reactions characteristic of the carbon-carbon double bond, therefore, alkenes may undergo the free-radical substitution characteristic of alkanes. The most important of these addition and substitution reactions are summarized below, and will be discussed in detail in following sections. 

Much of the essential physical chemistry of the hydrophobic effect has emphasized the transfer of small organics from the gas phase to water. As we have said, hydrocarbons have very low solubilities in water. While this is the characteristic feature of the hydrophobic effect, other thermodynamic effects are seen, including unusual entropy effects and often large heat capacity effects. To a very good approximation, AG° of transfer scales with surface area of the hydrocarbon that is exposed to water on dissolution. The exact scaling factor is debated and appears to depend on context. Values as low as 15 cal/ mol in AG° for every A of exposed aliphatic or aromatic hydrocarbon and as high as 75 cal / mol "A are reported, but a more typical range is 30-50 cal/mol A. If we settle on 40 cal/mol A, and assume a surface area of 29 A for a CH2 in an alkane, then every additional CH2 adds 1.2 kcal/mol of destabilization in a hydrophobic effect. 

---