Final answer:
When compounds are similar in polarity, they separate based on their hydrophobic or hydrophilic interactions with the stationary phase in chromatography, as well as on the strength of their intermolecular forces, like dipole-dipole interactions and hydrogen bonding, affecting their boiling points.
Step-by-step explanation:
If compounds have similar polarities as in the alkene experiment, they must separate based on other physical properties such as boiling points. This is particularly relevant when you are using techniques like reverse phase High Performance Liquid Chromatography (HPLC). In such cases, compounds will separate based on their hydrophobic or hydrophilic interactions with the stationary phase of the chromatography column.
The ability of a compound to engage in dipole-dipole interactions, as seen with aldehydes and ketones, can affect boiling points and separation. Ethers, even with their polar single bonds, may not have the same effect on boiling points as molecules capable of hydrogen bonding like alcohols. In contrast, nonpolar compounds, such as those only containing C-H bonds, may have very low boiling points and separate first in chromatographic techniques due to weaker intermolecular forces.