Factors Affecting Boiling Point:
* Intermolecular Forces: The stronger the forces of attraction between molecules, the more energy is needed to overcome them and cause a change of state from liquid to gas.
* Ionic vs. Covalent Bonding: Ionic compounds generally have higher boiling points than covalent compounds because the electrostatic attraction between oppositely charged ions is very strong.
* Molecular Size and Mass: Larger molecules with higher molecular weights have more electrons and a greater surface area for intermolecular interactions, leading to higher boiling points.
* Polarity: Polar molecules have stronger intermolecular forces (dipole-dipole interactions) than nonpolar molecules.
Comparing the Compounds:
* MgO and CaO: Both are ionic compounds. They have very high boiling points due to the strong ionic bonds between the metal cations and oxide anions. CaO has a slightly higher boiling point than MgO because calcium is larger than magnesium, leading to weaker ionic bonds in MgO.
* NaCl: Another ionic compound, with a very high boiling point due to the strong ionic bonds between sodium and chloride ions.
* HCl: A covalent compound, with a much lower boiling point than the ionic compounds above. The dipole-dipole forces between HCl molecules are weaker than ionic bonds.
* CO2: A nonpolar covalent molecule with a very low boiling point. The only intermolecular forces present are weak London dispersion forces.
* SO2: A polar covalent molecule with a moderate boiling point. It has dipole-dipole forces, which are stronger than London dispersion forces.
Therefore, the compounds with the highest boiling points are:
1. MgO and CaO (ionic, strong bonds)
2. NaCl (ionic, strong bonds)
The order from highest to lowest boiling point would be:
1. MgO / CaO
2. NaCl
3. SO2
4. HCl
5. CO2
