Acetone, also known as propanone, is more polar than petroleum ether. Acetone has a significant dipole moment due to its carbonyl group (C=O), which makes it a polar solvent. The presence of this electronegative oxygen atom creates an area of partial negative charge, while the surrounding carbon atoms lead to partial positive charges. This polarity allows acetone to dissolve a variety of polar substances effectively.
On the other hand, petroleum ether is a mixture of hydrocarbons, primarily composed of pentane and hexane. These hydrocarbons have very weak dipole moments and are predominantly non-polar. As a result, petroleum ether cannot effectively interact with polar molecules.
In summary, the presence of the polar carbonyl functional group in acetone makes it more polar compared to petroleum ether, which is largely non-polar and composed of aliphatic hydrocarbons.