Lab 10: Evaporation and Intermolecular Attractions

Lab 10: Evaporation and Intermolecular Attractions

Data from the Lab and Pre-Lab

Questions:

1: In data table

2: The reason for the differences in the volatility between the different liquids can be founds in their bonds. Methanol, which was the most volatile, had the lowest number of hydrogen bonds, and was the smallest. Therefore it evaporated quickly. The next one was ethanol which was only slightly bigger than methanol so it evaporated more slowly. After that came water which has a double hydrogen bond, and after that came n-butanol. The reason that glycerin did not evaporate was that it was a fairly large molecule with many bonds, so it gathered heat instead of losing it to evaporation.

3: Water and methanol had similar molar masses, but their speeds of evaporation differ greatly. The reason for this is that water had two hydrogen bonds and methanol only has one. Waters intermolecular forces are higher than that of methanol.

4: The number of OH groups affects the evaporation rates of liquids because it is a hydrogen bond. The more OH groups a liquid has, the harder it will be for it to evaporate, because it requires more energy.