Alkanes - Definition. Properties, Formulas, FAQs

Hydrocarbons

Its molecular formula is CH_4, and it comes from the simple alkane methane, ethane, propane, and butane. An alkane structural formula is for a compound with only one covalent bond

Methane

An additional carbon atom is attached to another carbon atom via a covalent bond in a long-chain alkane molecule. A total of four single covalent bonds are formed between each atom and enough hydrogen atoms. Oxana is a long-chain hydrocarbon. Alkanes with eight carbons have the molecular formula $\mathrm{C}_8 \mathrm{H}_{18}$.

Physical Properties of Alkanes

1. Alkane Solubility

1. Generally speaking, alkanes are non-polar molecules due to the fact that carbon and hydrogen have little difference in Electronegativity, and they have a covalent bond between them.

2. A general rule of thumb is that polar molecules are soluble in polar solvents, whereas nonpolar molecules are soluble in nonpolar solvents. The nature of alkanes, therefore, is hydrophobic, meaning they are insoluble in water.

3. They are, however, soluble in organic solvents since overcoming existing Van Der Waals Forces and generating new ones takes about the same amount of energy.

2. Alkanes and their boiling points

1. With increasing molecular weight, alkanes have a higher boiling point,

2. A comparison of the boiling points of straight-chain alkanes and their structural isomers reveals that the former has a higher boiling point.

3. Melting points of Alkanes

1. An alkane's melting point increases as its molecular weight increases, i.e., it is proportional to its boiling point.

2. There is a strong attraction between alkanes that makes it hard to overcome them due to their solid nature.

3. The melting point of even-numbered alkanes tends to be higher than that of odd-numbered alkanes because the even-numbered alkanes form well-organized crystal alkane structures in solid-state, making them difficult to seep out.

Molecular and Structural Formula of Alkane

Condensed forms of alkane structural formulas are available. Pentane is a chemical compound containing three CH₂ methylene groups in the middle of the chain. The structural formula can be written by grouping them together. The first five unbranched alkane formulas are listed below.

Chemistry of Alkane Formulas

There is a wide variety of information to be found in organic compound formulas. The atomic numbers for molecules of a compound can be calculated by looking at a molecular formula, like the one for octane. Alkanes have various properties, including chemical, physical, and physicochemical, and the Molecular Formula of $\mathrm{C}_8 \mathrm{H}_{18}$ can apply to many of them.

Each of these compounds has a specific alkane structure formula showing the atoms in the molecule arranged in a certain order. Isomerization refers to the process of changing the alkane structure of organic compounds with the same molecular formula.

Many organic compounds can be converted into alkanes. The functional groups of many organic molecules are alkane groups substituted for the hydrogen atom of the basic molecule. Because of these factors, alkanes are sometimes named for organic compounds.

Alkane Formula with Branched Chains

Alkanes contain carbon atoms that form straight chains, branched chains, and rings like other organic compounds. A straight-chain alkane, a branched-chain alkane, and a cycloalkane are examples of alkanes. Alkane molecules with straight and branched chains have a molecular formula of $\mathrm{C}_n \mathrm{H}_{2 n+2}$, and those with cyclic chains are $\mathrm{C}_n \mathrm{H}_{2 n}$..

Related Topics link

• Aromatic Compounds
• Examples of Bases
• Lewis Acids and Bases
• Saturated Hydrocarbons
• Isomerism

Alkyl Group

A carbon-hydrogen bond in an alkane molecule becomes a carbon-substituent bond when a substituent, like a halogen, bonds to it. The process of methane reacting with chlorine forms chloromethane, which is a new compound CH₃ atoms are joined to chlorine atoms in the new compound.

$\mathrm{CH}_4+\mathrm{Cl}_2 \xrightarrow{\text { UV light }} \mathrm{CH}_3 \mathrm{Cl}+\mathrm{HCl}$

The term alkyl group refers to the removal of hydrogen from one bond in a diketone. This Alkyl group is also commonly represented by the letter R, as opposed to the letter X representing halogens. This reaction between methane and chlorine can be generalized as

$\mathrm{R}-\mathrm{H}+\mathrm{X}_2 \xrightarrow{\text { UV light }} \mathrm{R}-\mathrm{X}+\mathrm{HX}$

Also read :

Some Solved Examples

Question 1: In which hydrocarbon are all four valencies of carbon linked together with a single bond?

A. Alkanes

B. Alkenes

C. Alkynes

D. None of the above

Solution:

In Alkanes, all four valencies of carbon are linked together with single bond

Hence, the correct answer is option (A)

Question 2: Number of optical isomers possible for 2-chlorobutane __________.

Solution:

Hence, the answer is (2).

Question 3: The major product when methane reacts with chlorine in the presence of UV light is:
A. $\mathrm{CH}_2 \mathrm{Cl}_2$
B. $\mathrm{CH}_3 \mathrm{Cl}$
C. $\mathrm{CHCl}_3$
D. $\mathrm{CCl}_4$

Solution:

Free radical substitution occurs under UV light.
First substitution gives chloromethane ( $\mathrm{CH}_3 \mathrm{Cl}$ ).

Hence, the correct answer is option (B)