List All Types Of IMFs That Would Occur In Each Of The Following A. CH_3CF_3 B. CCl_4 C. SO_2 D. BrF List The Dominant Type Of IMF For The Pure Substances, Then Rank The Strength Of Each Compound Based On IMFs Within The Samples. Circle All Of The Species Below That Can Form A Hydrogen Bond In Its Pure Form. Explain Why The Other Species Couldn’t
The correct answer and explanation is:
Explanation of Intermolecular Forces (IMFs)
Intermolecular forces (IMFs) are the forces between molecules, influencing boiling points, melting points, and solubility. The main types of IMFs are London Dispersion Forces (LDFs), Dipole-Dipole Interactions, and Hydrogen Bonding. The strength of these IMFs varies based on molecular structure and the presence of electronegative atoms or polar bonds.
Answers for the Given Compounds:
A. CH₃CF₃
- IMFs Present:
- London Dispersion Forces (LDFs) (present in all molecules).
- Dipole-Dipole Interactions (due to polar C-F bonds).
- Dominant IMF: Dipole-Dipole Interactions.
- Reasoning: The molecule is polar because of the highly electronegative fluorine atoms creating a dipole moment.
B. CCl₄
- IMFs Present:
- London Dispersion Forces (LDFs) only.
- Dominant IMF: London Dispersion Forces.
- Reasoning: CCl₄ is nonpolar because the symmetrical tetrahedral structure cancels out dipole moments.
C. SO₂
- IMFs Present:
- London Dispersion Forces (LDFs).
- Dipole-Dipole Interactions (due to the bent structure making the molecule polar).
- Dominant IMF: Dipole-Dipole Interactions.
- Reasoning: SO₂ is polar because of its bent shape and the presence of lone pairs on the sulfur atom.
D. BrF
- IMFs Present:
- London Dispersion Forces (LDFs).
- Dipole-Dipole Interactions (due to the difference in electronegativity between Br and F).
- Dominant IMF: Dipole-Dipole Interactions.
- Reasoning: BrF is polar due to the electronegativity difference between bromine and fluorine.
Ranking of IMF Strength
Based on the dominant IMF in each compound:
- SO₂ (Dipole-Dipole; bent polar structure increases IMF strength).
- CH₃CF₃ (Dipole-Dipole; fluorine atoms create a strong polar environment).
- BrF (Dipole-Dipole; lower polarity compared to CH₃CF₃).
- CCl₄ (Only LDFs, weakest overall).
Hydrogen Bonding
Can Form Hydrogen Bonds: None of these compounds can form hydrogen bonds in their pure form.
- Explanation: Hydrogen bonding occurs when hydrogen is covalently bonded to highly electronegative atoms (N, O, or F) and interacts with a lone pair on another electronegative atom. None of these molecules have hydrogen directly attached to N, O, or F.
- Why Others Cannot:
- CH₃CF₃: Contains fluorine, but the hydrogens are not directly bonded to it.
- CCl₄: Lacks hydrogen atoms.
- SO₂: No H-N, H-O, or H-F bonds.
- BrF: Lacks hydrogen atoms.
In summary, the strongest IMFs and ranking depend on the molecule’s polarity, and none of these compounds exhibit hydrogen bonding due to the absence of a suitable H-N, H-O, or H-F bond.