Chapter 14, Problem 8SA

Name the first eight members of the alkane series. What are some useful products and properties of alkanes?

To determine

The first eight members of the alkane series.

Answer to Problem 8SA

The first eight members of the alkane series are,

$\begin{array}{cc}\text{Name}& \text{Molecular formula}\\ \text{Methane}& {\text{CH}}_{\text{4}}\\ \text{Ethane}& {\text{C}}_{\text{2}}{\text{H}}_{\text{6}}\\ \text{Propane}& {\text{C}}_{\text{3}}{\text{H}}_{\text{8}}\\ \text{Butane}& {\text{C}}_{\text{4}}{\text{H}}_{\text{10}}\\ \text{Pentane}& {\text{C}}_{\text{5}}{\text{H}}_{\text{12}}\\ \text{Hexane}& {\text{C}}_{\text{6}}{\text{H}}_{\text{14}}\\ \text{Heptane}& {\text{C}}_{\text{7}}{\text{H}}_{\text{16}}\\ \text{Octane}& {\text{C}}_{\text{8}}{\text{H}}_{\text{18}}\end{array}$

Explanation of Solution

Alkanes are classified as hydrocarbons and are saturated. The general formula of an alkane is ${\text{C}}_n{\text{H}}_{\text{2}n\text{+2}}$. The name of alkane has a suffix ‘–ane’ with it. Methane is the first member of alkane series followed by ethane, propane and butane. The number of carbon atoms in methane is 1. The number of carbon atom increases by one as we move ahead in the alkane series.

The name of alkanes after butane are written according to the number of carbon atoms in its formula, indicated by Greek prefixes. For example, the alkane of formula ${\text{C}}_{\text{5}}{\text{H}}_{\text{12}}$ has 5 carbon atoms and the Greek prefix ‘Penta-’ is used with the suffix ‘-ane’. The name of an alkane is thus pentane. Similarly, the name of next alkanes in the alkane series is hexane, heptane and octane. The first eight members of the alkane series are,

$\begin{array}{cc}\text{Name}& \text{Molecular formula}\\ \text{Methane}& {\text{CH}}_{\text{4}}\\ \text{Ethane}& {\text{C}}_{\text{2}}{\text{H}}_{\text{6}}\\ \text{Propane}& {\text{C}}_{\text{3}}{\text{H}}_{\text{8}}\\ \text{Butane}& {\text{C}}_{\text{4}}{\text{H}}_{\text{10}}\\ \text{Pentane}& {\text{C}}_{\text{5}}{\text{H}}_{\text{12}}\\ \text{Hexane}& {\text{C}}_{\text{6}}{\text{H}}_{\text{14}}\\ \text{Heptane}& {\text{C}}_{\text{7}}{\text{H}}_{\text{16}}\\ \text{Octane}& {\text{C}}_{\text{8}}{\text{H}}_{\text{18}}\end{array}$

Conclusion:

Therefore, the first eight members of the alkane series are,

$\begin{array}{cc}\text{Name}& \text{Molecular formula}\\ \text{Methane}& {\text{CH}}_{\text{4}}\\ \text{Ethane}& {\text{C}}_{\text{2}}{\text{H}}_{\text{6}}\\ \text{Propane}& {\text{C}}_{\text{3}}{\text{H}}_{\text{8}}\\ \text{Butane}& {\text{C}}_{\text{4}}{\text{H}}_{\text{10}}\\ \text{Pentane}& {\text{C}}_{\text{5}}{\text{H}}_{\text{12}}\\ \text{Hexane}& {\text{C}}_{\text{6}}{\text{H}}_{\text{14}}\\ \text{Heptane}& {\text{C}}_{\text{7}}{\text{H}}_{\text{16}}\\ \text{Octane}& {\text{C}}_{\text{8}}{\text{H}}_{\text{18}}\end{array}$

To determine

The useful products and properties of alkanes.

Answer to Problem 8SA

Some of the useful products of alkanes are natural gas, petroleum, gasoline, kerosene, fuel oil, petroleum jelly, detergents and cosmetics. There are many useful properties of alkanes. The alkanes can be solid, liquid or gases. Alkanes are immiscible in water. Alkanes in presence of oxygen undergo a combustion reaction to form carbon dioxide and water. Alkanes are in general less reactive.

Explanation of Solution

There are many useful products that contain alkanes. The natural gas used for cooking or heating purposes contains methane. Propane and butane are used for the similar purposes. Petroleum and gasoline are also composed of alkanes. The general formula of an alkane is ${\text{C}}_n{\text{H}}_{\text{2}n\text{+2}}$. These products contain alkanes that are present lower in the alkane series that is the value of $n$ is between 1 to 10.

The higher alkanes that have $n$ greater than 10 are present in kerosene, fuel oil, petroleum jelly, detergents, insecticides and cosmetics.

There are many useful properties of alkanes. Alkanes can be solid, liquid or gas. For example, methane is a gas and pentane is a liquid. The alkanes with even higher values of $n$ are solid. Alkanes, in general, do not have any color and are non-polar. They are not soluble in water and dissolve only in a non-polar solvent.

Alkanes undergo combustion reaction very easily. The combustion of alkanes produces a large amount of energy in the form of heat and the product formed are carbon dioxide and water. The alkanes consist of $\text{C}-\text{C}$ bonds and $\text{C}-\text{H}$ bonds that have to be broken for any chemical reaction. These bonds are strong and hence alkanes are relatively less reactive.

Conclusion:

Some of the useful products of alkanes are natural gas, petroleum, gasoline, kerosene, fuel oil, petroleum jelly, detergents and cosmetics. There are many useful properties of alkanes. The alkanes can be solid, liquid or gases. Alkanes are immiscible in water. Alkanes in presence of oxygen undergo a combustion reaction to form carbon dioxide and water. Alkanes are in general less reactive.