Given the two substances Sodium Nitrate (NaNO3) and Urea ([NO2]2CO), why is it that urea has a lower boiling point? I thought that the nitrate would because urea has the double bond which makes it more stable.

Urea is covalently bonded. NaNO3 is an ionic compound. Generally ionic compounds have a higher boiling point than organic compounds.

To understand why urea has a lower boiling point than sodium nitrate, you need to consider the difference in their chemical properties and bonding.

First, let's compare the bonding in these two compounds. Sodium nitrate (NaNO3) is an ionic compound composed of sodium cations (Na+) and nitrate anions (NO3-). Ionic compounds have strong electrostatic attractions between the positively and negatively charged ions, which require a significant amount of energy to break these attractive forces and convert the compound into a gaseous state. As a result, ionic compounds generally have higher boiling points.

On the other hand, urea ([NH2]2CO) is an organic compound with covalent bonding. Covalent compounds generally have relatively weaker intermolecular forces (forces between molecules) compared to the strong ionic bonds in ionic compounds. These intermolecular forces in urea arise from hydrogen bonding and dipole-dipole interactions. These intermolecular forces are weaker than the forces in the ionic bond, resulting in a lower boiling point for urea.

The double bond you mentioned in urea's structure is a carbon-oxygen double bond, which does not significantly affect the boiling point compared to the primary factor, which is the difference in bonding between ionic and covalent compounds.

Therefore, urea has a lower boiling point compared to sodium nitrate because it is a covalent compound with weaker intermolecular forces, while sodium nitrate is an ionic compound with stronger ionic bonds and intermolecular forces.