CH 13 Smartbook

Colligative properties are properties of a solution that depend only on the _____ of solute particles in a given volume of solution, not on their _____.

number; type

The most abundant component of a solution is usually called the ___ , whereas the other dissolved components are called ___ .

solvent solute

Which of the following statements correctly describe solutions consisting of gases and/or solids? Select all that apply.

Gas-gas solutions form readily because all gases are miscible with each other. Gas-solid solutions are important as catalysts. A gas may dissolve in a solid by occupying the spaces between the solid particles.

A solution contains 0.32 mol naphthalene in 5.50 mol of toluene at 32oC. Pure toluene has a vapor pressure of 41 torr at this temperature. Which of the following options correctly solve for both P and ΔP for this solution? Select all that apply.

P = 5.500.32+5.50 x 41 = 39 torr ΔP = 0.320.32+5.50 x 41 = 2.3 torr

Which of the following statements correctly explain the effect of a nonvolatile solute on the vapor pressure of a solution? Select all that apply.

Solute particles on the solution surface decrease the number of solvent particles that can escape. Vapor pressure is lowered. The entropy of the solution is higher than that of the pure solvent. Solvent has less tendency to vaporize, and the vapor pressure is lowered.

Which of the following are applications of freezing point depression? Select all that apply.

Refining petroleum Car antifreeze "Salting" frozen roads Biological antifreeze

Which of the following are applications of osmotic pressure? Select all that apply.

Safe delivery of nutrients or drugs intravenously Food preservation Regulation of bodily water volume Absorption of water in trees

Which of the following options that correctly describe Henry's law for gases? Select all that apply. Sgas = kH x Pgas

Sgas is the solubility of the gas at a particular temperature. This law shows that the solubility of a gas increases with pressure. Pgas is the partial pressure of the gas above the liquid.

How does the presence of a strong electrolyte in solution affect the colligative properties of a solution when compared to the same number of moles of a nonelectrolyte solute?

The electrolyte dissociates or ionizes to give a larger number of moles of dissolved particles, with a greater effect on the colligative properties.

Which of the following options correctly describe a solution that is in contact with undissolved solute at a given temperature? Select all that apply.

Undissolved solute is in equilibrium with dissolved solute. The rate at which solute is dissolving is equal to the rate at which solute particles are crystallizing from solution. The concentration of dissolved solute will not change.

Concentrated aqueous HCl contains 38% w/w HCl. Calculate the mass of water present in 250. g of this solution.

155 g H2O

A solution contains 25.0 g ethanol (C2H5OH; molar mass 46.07 g/mol) in 500. g H2O (molar mass 18.02 g/mol) at 23oC. If the vapor pressure of pure H2O at this temperature is 20.57 torr, What is the vapor pressure of the solution?

20.1 torr

The compound Ca(NO3)2 dissociates in water to form ___ mol of ions for every 1 mol of solute and its van't Hoff factor i is expected to be ___ in an ideal solution. The compound urea (CH4N2O) has an expected i value of ___ .

3 3 1

What are the features of a nonvolatile, nonelectrolyte solute? Select all that apply.

A solute that has a negligible vapor pressure at the boiling point of the solvent A solute that dissolves but produces no ions in solution

Certain substances such as alcohols are able to dissolve fairly readily in both polar and nonpolar solvents. Which statements correctly explain this behavior? Select all that apply.

Alcohols form strong interactions with both types of solvent. The hydrocarbon portion of the alcohol interacts with the nonpolar solvent through dispersion forces. Alcohols have dual polarity since they possess a polar OH group as well as a nonpolar hydrocarbon portion.

Which of the following statements correctly describe the molality and molarity of a solution? Select all that apply.

For a dilute aqueous solution molality and molarity are nearly equal. Both molarity and molality express concentration in terms of moles of solute. M must be calculated using the volume of the solution, not the volume of the solvent.

Which of the following statements correctly describe freezing point depression for a solution? Select all that apply.

Freezing point depression is proportional to the molality of the solution. ΔTf is a positive value. The freezing point constant Kf is characteristic of the solvent.

Which of the following options correctly describe the effect of temperature on the solubility of a solid in a given solvent? Select all that apply.

In general, solids are more soluble at higher temperatures than at lower temperatures. There is no clear correlation between ΔHsoln and solubility at different temperatures.

Which of the following statements correctly defines colligative properties?

Properties of a solution that depend only on the number of dissolved solute particles

Which of the following options correctly show the relationships between solute concentration and solution vapor pressure? Select all that apply.

Psolvent = Xsolvent x P°solvent ΔP = Xsolute x P°solvent

Which of the following options describe situations in which hydrogen bonding will be observed between the solute and the solvent? Select all that apply.

Solvent contains OH or NH groups, solute contains N, O, or F atoms. Solvent and solute both contain OH or NH groups. Solvent contains N, O, or F; solute contains OH or NH groups

Which of the following options correctly reflect the effect of a nonvolatile solute on the boiling point of a solution? Select all that apply.

The lower the concentration of the nonvolatile solute, the higher the vapor pressure of the solution. Boiling point elevation occurs because the presence of a nonvolatile solute lowers the vapor pressure of the solvent. The greater the concentration of the solute, the higher the boiling point will be. A solution boils at a higher temperature than the pure solvent.

Which of the following statements correctly describe the vapor pressure of a solution containing a volatile nonelectrolyte solute? Select all that apply.

The vapor pressure of each volatile component can still be calculated using PA = XAPoA. The fraction of the volatile component in the vapor will be greater than that in the solution. The vapor pressures of both volatile components will be lowered.

Which of the following options correctly describe the different ways of expressing the concentration of a solution? Select all that apply.

To calculate mole fraction for a given mass of a reactant or product, the masses of all solution components must be known. The unit for molality (symbol m) is mol/kg.

To convert a concentration unit based on mass to one based on volume, the of the solution will be required.

density

Freezing point _____ is observed for solutions containing nonvolatile solutes. The vapor pressure of a solution is _____ than that of the pure solvent, and the solution therefore freezes at a _____ temperature.

depression, lower, lower

I2 (s) has a very low solubility in H2O (l) because the weak _____ forces between I2 and H2O are not strong enough to replace the _____ between the H2O molecules.

dipole-induced dipole; hydrogen bonds

The van't Hoff factor i is a measure of the effect of a solute on colligative properties. It is given by the ratio: measured value for ___ solution/expected value for ___ solution. For any electrolyte i > 1 because an electrolyte ___ in solution.

elctrolyte nonelectrolyte dissociates

Henry's law states that the solubility of a ______ in a solvent is directly proportional to the ______.

gas; pressure of that gas above the solution

A solute that is nonvolatile is one that has a relatively _____ vapor pressure at the boiling point of the solvent.

low

A solution containing a nonvolatile solute will have a(n) ___ vapor pressure than the pure solvent. The change in the vapor pressure is proportional to the ___ fraction of the solute in the solution.

lower mole

An alcohol possesses a(n) ___ hydroxyl (-OH) group and a(n) ___ hydrocarbon chain. Due to its ___ polarity, an alcohol is able to dissolve in both polar and nonpolar solvents.

polar nonpolar dual

A solution of 1.90 g of a nonelectrolyte in 500.0 mL of water at 27.0°C has an osmotic pressure of 39.5 mmHg. What is the molar mass of the compound?

1.71 × 103 g/mol

If more solute is added to a solvent, more than is able to dissolve at a given temperature, a(n) ___ will be established between dissolved and undissolved solute. The rate at which solute continues to dissolve is ___ to/than the rate at which solute crystallizes from solution.

equilibrium equal

A solution forms when the attractive ___ between the solute and solvent are ___ in strength to the solvent-solvent and solute-solute attractions and are therefore able to replace them.

forces similar

A solution containing 1 mol of a strong electrolyte will have a(n) _____ effect on the colligative properties of the solution than 1 mol of a nonelectrolyte. A strong electrolyte will dissociate or ionize in aqueous solution, and therefore the total number of dissolved solute particles is _____ for 1 mol of a strong electrolyte than for 1 mol of a nonelectrolyte solute.

greater; greater

A solution containing a nonvolatile solute always boils at a _____ temperature than the pure solvent. The vapor pressure of the solution is _____ than the vapor pressure of the pure solvent; hence the solution must be heated to a _____ temperature in order for the vapor pressure to equal the external pressure.

higher; lower; higher

A solution contains 44.0 mL of benzene (C6H6; d = 0.877 g/mL) in 125 mL of hexane (C6H14; d = 0.660 g/mL). Select all the options that correctly show the calculations needed to calculate both the mass % and the volume % of the solution.

mass of hexane = 82.5 g mass % = 38.6g121.2g × 100 = 31.8% w/w The molecular formulas and molar masses of the compounds are not required for this calculation.

In a liquid solution containing two or more volatile components, the mole fraction of the most volatile component will be ___ than that of any other component(s) in the vapor above the solution.

more

Most solids are _____ soluble in a particular solvent at higher temperatures than at lower temperatures, although there are some exceptions. The solubility of a gas in water will generally _____ as temperature increases.

more; decrease

True or false: All gases are miscible with each other.

t

In an ideal solution of a strong electrolyte, the van't Hoff factor i is equal to _____.

the number of moles of particles produced by dissociation of 1 mol of the electrolyte