Question

Rank the following molecules from highest to lowest boiling point: CO2, H2S, NaF, NH3. Explain your ranking using IMF’s.

Answer 1

Answer:

NaF>NH3>H2S>CO2

Explanation:

The boiling point of a substance depends on the magnitude of electronegativity difference and the type of bond between the atoms of the compound in question.

NaF is an ionic substance. Ionic substances have a high melting and boiling point due to the fact that the ionic lattice contains a large number of ions. This means that a lot of energy is usually required to overcome this ion-ion interaction therefore ionic compounds usually have high melting and boiling points.

Nitrogen is more electronegative than sulphur hence NH3 is more polar than H2S and consequently NH3 has a higher boiling point than H2S due to stronger dipole-dipole interaction.

CO2 is a nonpolar molecule hence it has the lowest boiling point. Only weak dispersion forces exist in CO2.