What are the physical properties of alkanes and how do they vary with increasing molecular size?

The physical properties of alkanes vary with increasing molecular size.

Alkanes are hydrocarbons that consist of only single covalent bonds between carbon atoms. They are nonpolar molecules, which means they have no charge separation and are therefore insoluble in water. Alkanes have low boiling points and are gases or liquids at room temperature, depending on their molecular size. The smaller alkanes, such as methane and ethane, are gases at room temperature, while the larger alkanes, such as octane and nonane, are liquids.

As the molecular size of alkanes increases, their boiling points and melting points also increase. This is because larger molecules have more electrons and a larger surface area, which leads to stronger intermolecular forces between molecules. These forces are known as London dispersion forces, and they increase with increasing molecular size. As a result, larger alkanes have higher boiling points and melting points than smaller alkanes.

The solubility of alkanes in water also decreases with increasing molecular size. This is because the nonpolar nature of alkanes makes them insoluble in polar solvents such as water. However, alkanes can dissolve in nonpolar solvents such as hexane and benzene.

In summary, the physical properties of alkanes vary with increasing molecular size. Larger alkanes have higher boiling points and melting points, and are less soluble in water than smaller alkanes.