Intermolecular Strength Hands-on Lab Investigative phenomenon: Rubbing alcohol on your skin dries within seconds of application. How does it dry so quickly? For this investigative phenomenon, compare the intermolecular strengths of two substances by comparing their boiling points. Intermolecular strength refers to the force of attraction between atoms or molecules within a substance. Substances with stronger attractions between molecules will need more kinetic energy to overcome these attractive forces. The heating of a substance is the transfer of thermal energy to kinetic energy within molecules. Download the lab report and follow the instructions for the hands-on lab option. You will submit your completed lab report.