Depends on the atmospheric pressure. Boiling occurs when vapor pressure is equivalent to atmospheric pressure. If the pressure of the atmosphere is still atmospheric pressure (760 torr / 1 bar / 101.25 kPa) then the boiling point should remain the same.

For gases heavier than air, however, it will require fewer moles of gas to achieve that pressure. For instance if you had a two chambers, one with argon and one with air, each with equivalent molar amounts of gas, then the pressure in the argon chamber would be higher and therefore the bp of the liquid in the argon chamber would be higher due to the fact that one mole of argon weighs more than one mole of air. Does that make sense?

Heptane weakest. Pentanoic acid strongest. Hexanoyl… do you mean hexanol?

By NH4, I assume you mean NH4+. Compounds that contain NH4+ have ionic bonds, and thus should have higher boiling points than compounds without ionic bonds, like CH3OH.

Thank you for this long and eloquent response, Marc.

Just a bit clarity:

1) “Electronegativity” is a measurement of how strongly an atom wishes to hold onto its valence electrons. There are at least 5 different versions of this value, each calculated a slightly different way, though most chemists refer to (Linus) Pauling’s electronegativity, as he came up with the first method of calculation. Incidentally, his method only measures electronegativity differences (see below), so the electronegativity of hydrogen was SET at 2.20, and every other atom’s electronegativity is relative to that value.

2) “Polarity” is a term that reflects how DIFFERENT the electronegativities are of two bonded atoms.
a) That is, polarity is always relative to the electronegativity difference between TWO atoms, and it not related to any one atom.
b) bonds with an electronegativity DIFFERENCE greater than 0 (that is, any bond that is not between two identical atoms, which is considered to be a pure covalent bond) is technically a polar bond, but the convention is that the difference should be greater than 0.5 to be considered realistically polar.
c) once that difference is greater than some threshold (different chemists have identified the cut-off at 1.7, 1.8, 2.0, or 2.2 that I know of), the electrons that compose the bond have been completely (or nearly completely) captured by the more electronegative atom. This results in one atom having a full negative charge (an anion) and one atom having a full positive charge (a cation). They are no longer sharing the electrons, but the electrostatic attraction of two oppositely charged ions, called the ionic bond, is quite strong; frequently of higher binding energy than typical covalent bonds (non-polar or polar).
d) the reality is that even with the two atoms that having the highest (F) and lowest electronegativities (Fr), the difference in electronegativity still results in a bond with only about 92% ionic character. That is, nearly every bond that we refer to as “ionic” actually still has a little bit of covalent (i.e., shared electron) character.

I hope that this helps. I have no idea how long ago you posted your question.

Marc