Question

1. for the table below, specify the dominant intermolecular force involved for each substance in the space immediately following the substance. then in the last column, indicate which member of the pair you would expect to have the higher boiling point.

substance #1 substance #2 dominant intermolecular force substance with higher boiling point
a. hcl(g) i₂ london - dispersion forces
b. ch₃f ch₃oh
c. h₂o h₂s
d. sio₂ so₂
e. fe kr
f. ch₃oh cuo
g. nh₃ ch₄
h. hcl(g) nacl
i. sic cu

Explanation:

Step1: Identify intermolecular forces

• HCl(g): Dipole - dipole forces as it is a polar molecule.
• CH₃F: Dipole - dipole forces due to its polarity.
• H₂O: Hydrogen bonding (strongest among common intermolecular forces for small molecules), also dipole - dipole and London dispersion forces.
• SiO₂: Covalent network solid, held together by strong covalent bonds.
• Fe: Metallic solid, held by metallic bonds.
• CH₃OH: Hydrogen bonding, dipole - dipole and London dispersion forces.
• NH₃: Hydrogen bonding, dipole - dipole and London dispersion forces.
• HCl(g): Dipole - dipole forces.
• SiC: Covalent network solid, held by strong covalent bonds.
• I₂: London dispersion forces as it is a non - polar molecule.
• CH₃OH: Hydrogen bonding, dipole - dipole and London dispersion forces.
• H₂S: Dipole - dipole forces due to polarity.
• SO₂: Dipole - dipole forces as it is polar.
• Kr: London dispersion forces as it is a noble gas (non - polar).
• CuO: Ionic solid, held by ionic bonds.
• CH₄: London dispersion forces as it is non - polar.
• NaCl: Ionic solid, held by ionic bonds.
• Cu: Metallic solid, held by metallic bonds.

Step2: Compare boiling points based on intermolecular forces

• Covalent network solids (SiO₂, SiC) have very high boiling points due to the strength of covalent bonds.
• Ionic solids (CuO, NaCl) have high boiling points due to strong ionic bonds.
• Metallic solids (Fe, Cu) have relatively high boiling points due to metallic bonding.
• Among molecular substances, those with hydrogen bonding (H₂O, CH₃OH, NH₃) have higher boiling points than those with only dipole - dipole (HCl, CH₃F, H₂S, SO₂) and London dispersion forces (I₂, CH₄, Kr).

Answer:

Substance #1	Dominant Intermolecular Force	Substance #2	Dominant Intermolecular Force	Substance with Higher Boiling Point
CH₃F	Dipole - dipole	CH₃OH	Hydrogen bonding	CH₃OH
H₂O	Hydrogen bonding	H₂S	Dipole - dipole	H₂O
SiO₂	Covalent bonds	SO₂	Dipole - dipole	SiO₂
Fe	Metallic bonds	Kr	London dispersion	Fe
CH₃OH	Hydrogen bonding	CuO	Ionic bonds	CuO
NH₃	Hydrogen bonding	CH₄	London dispersion	NH₃
HCl(g)	Dipole - dipole	NaCl	Ionic bonds	NaCl
SiC	Covalent bonds	Cu	Metallic bonds	SiC