Exam 10: Intermolecular Forces: The Uniqueness of Water

The relative energies (strengths) of the intermolecular forces present in each of four different pure substances are shown in the figure below. Which substance is most likely to be a solid at room temperature?

Dipole-dipole interactions typically are not as strong as ion-dipole interactions because ________

When potassium bromide dissolves in water, which picture best represents the solution?

Point c in the phase diagram below is the ________

Describe the utility of the Clausius-Clapeyron equation.

Which of the following compounds would you most appropriately call hydrophobic?

Gasoline is primarily a mixture of hydrocarbons and is sold with an octane rating that is based on a comparison with the properties of isooctane (C₈H₁₈), which has an enthalpy of vaporization of 35.8 kJ/mol and a boiling point of 98.2C. Determine the vapor pressure of isooctane on a very hot summer day when the temperature is 38C.

Which of the following gases do you expect to be least soluble in a polar solvent?

For the following unsaturated phospholipid, identify the hydrophilic and hydrophobic regions of the molecule and explain the rationale for your choice.

Which type of intermolecular interaction exists for all compounds?

For molecules or atoms with the same mass, which of the following typically is the weakest intermolecular interaction?

Ion-dipole forces always require________

At the point marked with a dot on the phase diagram, the solid will ________

The boiling point of HBr is higher than that of HCl because HBr has ________ (The dipole moments are 1.08 D for HCl and 0.82 D for HBr.)

Which statement about vapor pressure of a pure liquid is not correct?

Define the term vapor pressure.

Which of the following statements correctly characterizes the rate of evaporation of a liquid? I. Increases with increasing temperature because molecules have higher kinetic energies. II. Increases with increasing surface area of the liquid because more molecules are located at the surface. III. Decreases with stronger intermolecular forces because molecules are less able to escape from the surface of the liquid.

Which of the following substances has a solid whose freezing point will decrease with increasing pressure?

The relative energies (strengths) of the intermolecular forces present in each of four different pure substances are shown in the figure below. Which substance has the lowest melting point?

Identify the dominant intermolecular interaction(s) that must be overcome when solid CO₂ sublimes and H₂O melts.