Chem II Exam I

Which of the following must be overcome during the boiling of acetonitrile, CH₃CN? 1. dispersion forces 2. dipole-dipole forces 3. hydrogen bonds

1 and 2

A solution is formed at room temperature by vigorously dissolving enough of the solid solute so that some solid remains at the bottom of the solution. Which statement below is true? a. the solution is considered unsaturated b. the solution is considered supersaturated c. the solution would be considered unsaturated if it were cooled a bit to increase the solubility of the solid d. the solution is considered saturated e. non of the above are true

A

Which of the following statements is false? a. molecules with hydrogen bonding are more volatile than compounds with dipole-dipole b. rate of vaporization increases with increasing temperature c. rate of vaporization increases with decreasing strength of intermolecular forces d. rate of vaporization increases with increasing surface area e. none of the above statements are false

A (molecules with hydrogen bonding are more volatile than compounds with dipole-dipole)

How is colligative property different than the other properties of a solution?

A colligative property depends only on the number of solute particles in solution

What is sublimation?

A solid substance going directly into gas phase

Which of the following substances would you predict to have the highest ΔHvap? a. CH₃CH₂OH b. HOCH₂CH₂OH c. CH₃CH₂CH₂CH₃ d. HCl

B (HOCH₂CH₂OH)

Which of the following compounds will be most soluble in ethanol (CH₃CH₂OH)? a. acetone (CH₃COCH₃) b. ethylene glycol (HOCH₂CH₂OH) c. hexane (CH₃CH₂CH₂CH₂CH₂CH₃) d. trimethlyamine (N(CH₃)₃)

B (ethylene glycol (HOCH₂CH₂OH))

Choose the statement below that is true: a. a solution will form between two substances only if the solvent-solvent interactions are weak enough to overcome the solute-solent interactions b. a solution will form between two substances if the solute-solute interactions are small enough to be overcome by the solute-solute and solvent-solvent interactions c. a solution will form between two substances if the solute-solvent interactions are of comparable strength to the solute-solute and solvent-solvent interactions d. a solution will form between two substances if the solute-solute interactions are strong enough to overcome to overcome the solvent-solvent interactions e. none of the above are true

C (a solution will form between two substances if the solute-solvent interactions are of comparable strength to the solute-solute and solvent-solvent interactions )

Place the following compounds in order of increasing strength of intermolecular forces: CH₄, CH₃CH₂CH₃, CH₃CH₃

CH₄<CH₃CH₃<CH₃CH₂CH₃

Which of the following cannot be a colloid? a. a foam b. an emulsion c. an aerosol d. a homogenous mixture e. all of the above are colloids

D (a homogenous mixture)

Gas solubility increases with temperature.

False

The process in which a gas is transformed into a solid is called solidification.

False (sublimation)

Give the change in condition to go from a liquid to a gas

Increase heat or reduce pressure

Place the following substances in order of decreasing vapor pressure at a given temperature: BeF₂, CH₃OH, OF₂

OF₂>CH₃OH>BeF₂

Give the reason that antifreeze is added to a car radiator.

The freezing point is lowered and the boiling point is elevated

As the polarizability of molecules increases, the intermolecular forces between the molecules gets stronger.

True

Molality is independent of temperature, molarity is dependent of temperature.

True

What is the strong intermolecular force: CH₂F₂

dipole-dipole

What is the strong intermolecular force: CH₃CH₃

dispersion

The heat of deposition equals the negative of the heat of sublimation.

false

What is the strong intermolecular force: CH₃OH

hydrogen bonding

The boiling point of H₂O is much higher than that of the analogous molecule H₂S. This is due to

hydrogen bonding being much stronger in H₂O than in H₂S

Solutions having osmotic pressures less than those of body fluids are called

hyposomotic

What is the strong intermolecular force: LiI + H₂O

ion-dipole

What is the strong intermolecular force: LiI

ionic bonding