What are the physical properties of alkanes?

Alkanes are colourless, odourless, tasteless, and less dense than water, with low melting and boiling points.

Alkanes are a group of hydrocarbons, which are compounds made up of hydrogen and carbon atoms. They are the simplest type of hydrocarbons, with a single bond between the carbon atoms. This makes them saturated hydrocarbons. Alkanes are colourless and odourless, which means they do not have a distinct colour or smell. They are also tasteless, so they do not have a distinct flavour.

In terms of density, alkanes are less dense than water. This means that if you were to put an alkane in water, it would float on the surface. This property is important in many applications, such as oil spills, where the oil (which is made up of alkanes) floats on the surface of the water.

Alkanes have relatively low melting and boiling points. This is because they have weak intermolecular forces, specifically London dispersion forces, which are easy to overcome. The melting and boiling points increase as the number of carbon atoms in the alkane increases. This is because as the size of the molecule increases, the strength of the London dispersion forces also increases, requiring more energy to overcome.

Alkanes are also insoluble in water but soluble in organic solvents. This is due to the fact that water is a polar molecule, while alkanes are non-polar. Polar and non-polar substances do not mix well together, hence the insolubility of alkanes in water. However, alkanes can dissolve in organic solvents, which are also non-polar.

Finally, alkanes are less reactive than other hydrocarbons. This is because of the single bond between the carbon atoms, which is difficult to break. However, they can undergo combustion and substitution reactions under certain conditions.