If you add 1 mL of petroleum ether (a nonpolar solvent) to 5 mL of distilled water (a polar solvent), the two solvents will not readily mix due to their differing polarities.
Water is a highly polar molecule, meaning it has a partial positive charge on the hydrogen atoms and a partial negative charge on the oxygen atom. Petroleum ether, on the other hand, is a nonpolar solvent composed of mostly hydrocarbon molecules, which lack charged regions.
When you add the petroleum ether to water, it will form separate layers due to the differences in polarity. The petroleum ether, being nonpolar, will tend to cluster together and form a distinct layer on top of the water. This separation occurs because like dissolves like, meaning polar substances tend to dissolve in polar solvents, and nonpolar substances tend to dissolve in nonpolar solvents.
The two layers will not mix, and you'll observe the formation of two distinct phases. The petroleum ether layer will be less dense than water and will float on top. This phenomenon is similar to oil floating on water, as both petroleum ether and oil are nonpolar substances.
It's worth noting that petroleum ether is highly volatile and flammable, so it should be handled with caution.