Question

What generalization can you make about the densities of alkanes relative to the density of water?

Short answer

Answer: The densities of alkanes are generally less than the density of water, which causes them to float on water. This difference in density can be attributed to the weaker Van der Waals forces among alkane molecules compared to the stronger hydrogen bonds present in water molecules.

Step-by-step solution

Define alkanes and their properties

Alkanes are a class of hydrocarbons, with molecules that consist of hydrogen and carbon atoms. They have a general molecular formula of C_nH_(2n+2). Alkanes are nonpolar and do not dissolve in water. They have weaker intermolecular forces than water molecules, which is due to Van der Waals forces between their molecules.

Discuss the density of alkanes in general

The density of a substance can be calculated using the mass of the substance divided by its volume. In the case of alkanes, they consist of hydrogen and carbon atoms. As more carbon atoms are added in the chain, the mass of the alkane molecule increases, leading to an increase in the overall molecular weight of the alkane. But the volume also increases at a similar rate leading to an increase in density but not significantly.

Compare the density of alkanes to the density of water

The density of water is approximately 1 g/cm^3. The density of alkanes, on the other hand, tends to be lower than that of water. This is due to the weaker Van der Waals forces among alkane molecules compared to the stronger hydrogen bonds present in water molecules. Water has its unique properties due to these strong hydrogen bonds.

Make a generalization of alkane densities relative to the density of water

In general, the densities of alkanes are less than the density of water. This means that alkanes will generally float on water as they are less dense. This can be observed in cases such as oil spills, where the nonpolar oil (which contains alkanes) floats on top of the polar water.