Intermolecular Forces

Which substance has the weakest intermolecular forces?

• Substance A, boiling point of 75 °C

• Substance B, boiling point of 105 °C

• Substance C, boiling point of 25 °C

• Substance d, boiling point of 45 °C

The weaker the intermolecular forces of a substance the _____________ the boiling point

• higher

• lower

________________________ have the strongest intermolecular forces of attraction.

• Dipole- Dipole

• Dispersion

• Hydrogen Bonds

Hydrogen bonding occurs when hydrogen is bonded to N, O, or F.  Which of the following has hydrogen bonding?

• CBr₄
• NO₂
• H₂S
• NH₃

What explains the very high melting and boiling point of water

• Strong dipole-dipole bonds between water molecules
• Strong hydrogen bonds between water molecules
• Dispersion forces which are present in all molecules
• Asymmetrical shape of the polar bonds.

Does H₂S have hydrogen bonding?

• yes
• no

Does HF have hydrogen bonding?

• yes
• no

London forces are stronger in heavier atoms or molecules, and weaker in lighter atoms or molecules.  Which of these has the strongest London forces?

• F₂
• Br₂
• I₂
• Cl₂

Rank these in order of strength:
covalent bond
London forces
hydrogen bond
dipole-dipole attraction

• dipole-dipole>covalent bond>hydrogen bond>London
• London>dipole-diple>hydrogen bond>covalent bond
• covalent bond>hydrogen bond>dipole-dipole>London
• hydrogen bond>dipole-dipole>London>covalent bond

All molecules have London forces between them, but dipole-dipole and hydrogen bonding are so much stronger that when they are present we can ignore London forces.  Which of these has ONLY London forces?

• I₂
• NH₃
• OCl₂
• SH₂