Question

which do you think has a greater effect on evaporation
rate: molar mass or the type of intermolecular force(s) present? Explain your answer

Answer 1

The stronger the intermolecular force is, the slower the rate of evaporation will be. The intermolecular force is directly related to the bonds between molecules and the molar mass. The hydrogen bond is the strongest bond that molecules can obtain and if the bonds between molecules are strong then the attraction allows the solution to be held in its liquid state longer. Since the bond is strong it brings difficultly to break those bonds and when a liquid evaporates or becomes gaseous bonds need to be broken to transition to a gaseous state, it requires more energy to break those strong bonds which causes the rate of evaporation to be slower. The strength of intermolecular forces is directly related to the rate of evaporation, if the evaporation rate is higher, intermolecular forces are weaker. If the rate of evaporation is slower, the intermolecular forces are stronger.

Intermolecular forces are forces that hold molecules together at different strengths depending on the force itself. Hydrogen bonds are the strongest bond between molecules out of the possible three. When a hydrogen bond is present it becomes me difficult to break that bond between the molecules since the strength of the bond between the molecules is strong it then becomes more difficult for a solution in a liquid state to become gaseous which would entail bonds to be broken in turn would result in a slower evaporation rate. The weakest intermolecular force would be the London dispersion bond since the bond is the weakest it is less difficult to break apart the bonds in substances that have dispersion bonds present. Since the bonds are easier to break apart, solutions that consist of dispersion forces have a faster evaporation rate, the easier it is to break the bonds the less energy is required to do so therefore the rate of evaporation is quickened. Dipole-dipole forces are stronger then dispersion but weaker the hydrogen bonding which would directly mean its rate of evaporation is between hydrogen bonding and dispersion.