Evaporation and Intermolecular Attractions Lab

During the evaporation and intermolecular attraction lab, we dipped a thermometer into different solutions and recorded their temperature before they started to evaporate, and 240 seconds after they had started evaporating. To do this we used a LabQuest device which kept a running table/graph of temperature data from the thermometer.

Here is a picture of the pre-lab:

Here is a picture of my data table:

Questions:

Explain the differences in the difference in temperature of these substances as they evaporated. Explain your results in terms of intermolecular forces.

The differences in the difference in temperature of these substances did not very too much from each other. Methanol and ethanol had large changes while n-Butanol, glycerin, and water had smaller changes in temperature. This means that methanol and ethanol had weaker intermolecular forces as they were easier to overcome and had large vapor pressures, while n-Butanol, glycerin, and water had stronger intermolecular forces and smaller vapor pressures. 

Explain the difference in evaporation of any two compounds that have similar molar masses. Explain your results in terms of intermolecular forces.

Methanol and ethanol had similar molar masses and also had similar changes in temperature. Even though they were similar, methanol had a larger change in temperature because it had a smaller molar mass than ethanol. The London dispersion bonds are stronger in molecules with more molar mass because it is more polarized, which explains why methanol had a larger change in temperature [it had a smaller molar mass than ethanol]. 

Explain how the number of -OH groups in the substances tested affects the ability of the tested compounds to evaporate. Explain your results in terms of intermolecular forces.

Methanol, ethanol, water and n-butanol had one -OH group each, so their molar mass affected the temperature change more then glycerin. Glycerin had three -OH groups making it have the smallest temperature change. This happens because the hydrogen bonds are stronger when there are more -OH groups in a substance. The stronger the hydrogen bonds, the harder the forces are to break which is why glycerin had a smaller temperature change then all of the other substances.