Question 1
Rank the following in order of increasing boiling point.
a. NF3NF3
b. HFHF
c. F2
Question 2
Rank the following in order of increasing boiling point.
a. H2OH2O
b. SO2SO2
c. O2
Question 3
Answer to question 1
HF has the highest boiling point because of the hydrogen bonding and due to the polarity of the bond. Also, the size of the H-F molecule is small as compared two other given molecules. Therefore, the electron cloud is more concentrated on it leading to more electrostatic interactions.
The compound NF3NF3 does not have hydrogen bonding due to the lack of hydrogen atoms. This molecule has electronegativity difference between the atoms, due to which it has higher boiling point than the F2F2, which is a homoatomic molecule that does not have a polar or hydrogen bond.
Therefore, the correct order of increasing boiling point of the given compounds is:
F2F2 < NF3NF3 < HF
Answer to question 2
Both H2OandSO2H2OandSO2 are polar molecules, whereas O2O2 is a homonuclear diatomic non-polar molecule.
Usually, polar molecules have higher boiling points than non-polar molecules with comparable molar masses.
So, O2O2 has a lower boiling point than both H2OandSO2H2OandSO2.
H2OH2O exhibits both dipole-dipole forces and hydrogen bonding interactions but SO2SO2 displays only dipole-dipole forces. Hence, H2OH2O has a higher boiling point than SO2SO2.
So, the order of increasing boiling point for the given molecules is shown below:
O2<SO2<H2O
Answer to question 3
Order of increasing boiling point:
HCl<H2O<NaClHCl<H2O<NaCl
Ionic bonding exists in NaCl as it is made from sodium and chloride ions.
In H22O, there is hydrogen bonding since the hydrogen is attached to either N, O, or F.
There are dipole-dipole interactions in HCl due to the sufficient difference in electronegativities between hydrogen (2.2) and chlorine (2.8). All three compounds have London dispersion forces.
At room temperature, NaCl is solid. As a result, the strongest intermolecular attraction force of the group is found in NaCl. It requires a higher temperature to boil. The attractive forces between molecules determine the boiling point. The boiling point will rise as the attractive forces between molecules increase.
H22O is a liquid at room temperature and has a high boiling point, although less than NaCl, due to strong hydrogen bonding between molecules. HCl, which is normally a gas at room temperature, though only has dipole-dipole interactions which of the three compounds is the weakest attractive force.
Increasing order of forces:
Londondispersionforces<dipole−dipoleinteractions<Hydrogenbonding<IonicbondingLondondispersionforces<dipole−dipoleinteractions<Hydrogenbonding<Ionicbonding
Therefore,
Order of increasing boiling point:
HCl<H2O<NaCl