Evaporation and Intermolecular Attractions

Pre-lab and Data Tables





Calculations and Results

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

There are differences in the temperature of the substances as they evaporated is because of the different heat absorptions. In order to change a liquid to a gas, you must have enough energy to break the intermolecular bonds of the liquid. As the liquid evaporated into gas, it absorbs energy, in the form of heat, from the temperature probe. When the substance absorbed in the filter paper was evaporating, whether the drop of the temperature would be drastic or mild was due to how much energy was needed to break the intermolecular bonds.  

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

 The difference in evaporation of any two compounds that have similar molar masses is because of the intermolecular forces they contained. For instance, methanol and ethanol has similar molar masses with a respective 32.04 g/mol and 46.07g/mol, but methanol's change in temperature, 17.1 degrees Celsius, was very different than ethanol's change in temperature, 7.9 degrees Celsius. Ethanol has more molecules of CH than methanol, and therefore has more London dispersion forces than methanol. With a higher dispersion rate, ethanol evaporates quicker than methanol.

4) 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. 

The number of -OH groups in the substances tested affects the ability of the tested compounds to evaporate because the molecule of OH is a hydrogen bond, which is the strongest intermolecular force. This makes the liquid more resistant to evaporating and being broken apart into a gas. Thus, more -OH groups cause the substance to require more energy in order to evaporate. Glycerin, which contained 3 -OH groups, increased in temperature, while others with only one -OH group decreased, supporting our conclusion.

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