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If a problem strictly mentions molar mass, or states that there are no dipole-dipole interactions or hydrogen bonding, then increasing molar mass increases the Van de Waal forces because larger molecules can have larger instantaneous dipole moments. Larger Van de Waal forces means more attraction between moleculres, which means more energy is required to break those forces, which means a higher boiling point.
As many students have stated molar mass and boiling point are directly proportional. When it comes to intermolecular forces, London dispersion forces increase with larger molecules thus increasing the boiling point. Hope this helps!
Larger molar mass for the most part implies that the molecule has more electrons and the element is further down the periodic table hence more atomic shells. This allows the molecules to induce a greater dipole spontaneously as more electrons can spontaneously rearrange themselves and attract to a partial positive on the other molecule. Larger molar mass means stronger dispersion forces. The stronger the IMF's thew higher the boiling point will be because you need to put in more energy to break the IMF's between the molecules.
Higher molar mass means more protons and neutrons. More protons and neutrons means more electrons. More electrons means more movement of electrons. More movement of electrons means a potential for a greater disparity in the distribution of electrons-- a stronger dipole moment. Stronger dipole moment results in stronger intermolecular forces. These stronger intermolecular interactions require more energy, more heat, to force far apart, so there is a higher boiling point.
Higher molar masses mean that there are more electrons, which means more e- e- repulsion and shielding. This makes the distortion easier, which would increase the dipole moment, thus requiring a higher boiling point to break the bonds.
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