Chem 1312 chapter 12 SB
Which of the following are necessary components of a solution? Select all that apply.
One or more solutes Solvent
Match each change of enthalpy to the correct step of the solution process.
ΔH > 0 ----- Solvent-solvent and solute-solute intermolecular forces are overcome. ΔH < 0 ----- New solvent-solute intermolecular forces are formed.New solvent-solute intermolecular forces are formed. ΔH < 0 or ΔH > 0 ----- The solution process overall (including all interactions broken and formed) or the heat of solution
Which of the following statements correctly describe the thermodynamics of the solution process? Select all that apply.
ΔHsoln depends on the chemical nature of both the solvent and the solute. The sign of ΔHsoln is influenced by solvent-solvent, solute-solute, and solvent-solute interactions.
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.
ΔP = 0.32 / 0.32 + 5.50 x 41 = 2.3 torr P = 5.50 / 0.32 + 5.50 x 41 = 39 torr
Which of the following options correctly show the relationships between the mole fractions of solute and solvent and the vapor pressures of pure solvent and solution? Select all that apply.
ΔP = X2Po1 P1= X1Po1
An aqueous solution containing 3.50 g of the antibiotic sulfanilamide in 0.500 L of solution has an osmotic pressure of 0.988 atm at 23oC. Place the steps in order for determining the molar mass of sulfaniliamide.
1. T = 23 C + 273 = 295 K 2. M = π / RT 3. Moles of sulfaniliamide 4. Molar mass
Concentrated aqueous HCl contains 38% by mass of HCl. Calculate the mass of water present in 2.50 x 102 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
A 355-mL sample of an aqueous solution containing 0.320 g of an unknown molecular compound has an osmotic pressure of 45.1 mmHg at 42°C. What is the molar mass of the unknown compound?
393 g/mol
The vapor pressure of benzene (C6H6) at 20oC is 75 torr, What is the vapor pressure of a solution containing 15.0 g of the nonvolatile solute decanoic acid (C10H20O2) in 75.0 g of benzene?
69 torr
0.045 moles of H2SO4 are dissolved in 55.0 mL of H2O. Given that the density of H2O is 1.00 g/mL, calculate the mass percent of the H2SO4 in this solution.
7.4% Reason: Divide the mass of H2SO4 by the total mass of solution (mass H2SO4 + mass H2O) and then multiply by 100.
Which of the following options correctly describe a hydrophilic colloid? Select all that apply.
A hydrophilic colloid interacts with water via ion-dipole forces or hydrogen bonding. A hydrophilic colloid interacts favorably with water.
What are the features of a nonvolatile solute?
A solute that has a negligible vapor pressure at the boiling point of the solvent
Which of the following options correctly reflect the effect of a nonvolatile solute on the boiling point of a solution? Select all that apply.
A solution boils at a higher temperature than the pure solvent. The lower the concentration of the nonvolatile solute, the higher the vapor pressure of the solution. The greater the concentration of the solute, the higher the boiling point will be. Boiling point elevation occurs because the presence of a nonvolatile solute lowers the vapor pressure of the solvent.
Which of the following options correctly describes an ideal solution? Select all that apply.
An ideal solution obeys Raoult's law. The intermolecular forces exhibited in an ideal solution are similar in type and magnitude to those of the liquids that comprise the solution. An ideal solution has ΔHsoln = 0.
A 1.0 M solution of NaCl will have colligative properties of _____ magnitude than a 1.0 M solution of glucose. This is because the NaCl solution has a(n) _____ concentration of solute particles than the glucose solution.
Blank 1: greater, higher, more, or increased Blank 2: higher, greater, increased, or larger
A(n) _____ solution is defined as one that obeys Raoult's law.
Blank 1: ideal
A solution of a nonvolatile solute in a given solvent will always freeze at a _____ temperature than the pure solvent. This is due to the solution having a(n) _____ vapor pressure than the pure solvent.
Blank 1: lower or lesser Blank 2: lower, lesser, or smaller
A solution of a nonvolatile solute in a given solvent will always have a _____ vapor pressure than the pure solvent. Thus the solution will boil at a _____ temperature than the pure solvent.
Blank 1: lower, lesser, or smaller Blank 2: higher or greater
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.
Blank 1: lower, smaller, lesser, or decreased Blank 2: mole
A gas such as CO2 will be _____ soluble in water at 4oC than at 25oC.
Blank 1: more
A solute that has essentially no vapor pressure in comparison to the solvent is called a(n)
Blank 1: nonvolatile, non volatile, or non-volatile
Solubility is defined as the amount of ______ that is able to dissolve in a solvent at a particular ______.
Blank 1: solute Blank 2: temperature
______ properties of solutions depend only on the number (or concentration) of particles in solution, not their identity.
Colligative
Which of the following options correctly describe colloids? Select all that apply.
Colloidal particles are much larger than typical solute molecules. The dispersed phase and the dispersing medium of a colloidal suspension can be gases, liquids, solids, or a combination of different phases. A colloid is a dispersion of particles of one substance throughout a dispersing medium made of another substance.
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 processes occur when glucose (blood sugar) dissolves in water? Select all that apply.
Interactions between glucose molecules are broken. Glucose-water interactions are formed. Interactions between water molecules are broken.
Which expression of concentration takes the volume of the solution into account?
Molarity
Match each concentration term with the correct ratio each represents.
Molarity (M): mol of solute/ L of solution Molality (m): mol of solute / kg of solvent Parts by mass: mass of solute / mass of solution Mole fraction (X): mol of solute / total # of moles present
______ pressure is the pressure necessary to stop diffusion of water across a semipermeable membrane from a solution of low solute concentration to a solution of high solute concentration.
Osmotic
Which of the following statements correctly describe the osmotic pressure (π) of a solution? Select all that apply.
Osmotic pressure increases with temperature. Osmotic pressure is directly proportional to the molarity of the solution.
Match each of the terms in the equation for Raoult's law with the correct description. P1 = X1Po1
P1 ----- Vapor pressure of the solvent in the solution X1 ----- Mole fraction of the solvent in the solution Po1 ----- Vapor pressure of the pure solvent
Which of the following statements correctly defines colligative properties?
Properties of a solution that depend only on the number of dissolved solute particles
When a nonvolatile solute is dissolved in a given solvent, the vapor pressure of the resulting solution is equal to the product of the vapor pressure of the pure solvent and its mole fraction in the solution. This relationship is known as ______ law.
Raoult's
Two volatile molecular substances A and B are mixed. If the solution formed is an ideal solution, which of the following must be correct?
The intermolecular forces between A and B molecules are similar to those between A molecules and between B molecules.
Which of the following statements correctly describe the role played by disorder in the formation of a solution? Select all that apply.
The solution process is generally accompanied by an increase in disorder. Much of the order of a pure solvent and solute is destroyed when the solute dissolves in the solvent. An endothermic solution process may still occur if there is an increase in disorder for this process.
Which of the following options correctly describe the van't Hoff factor for the solution of an electrolyte? Select all that apply.
The van't Hoff factor is used to predict the colligative properties of an electrolyte solution. The van't Hoff factor is greater than 1 for electrolyte solutions. The van't Hoff factor is predicted from the number of particles the electrolyte will form after dissociation.
What is the effect on vapor pressure of dissolving a nonvolatile solute in a given solute?
The vapor pressure of the solution will be lower than that of the pure 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.
There is no clear correlation between ΔHsoln and solubility at different temperatures. In general, solids are more soluble at higher temperatures than at lower temperatures.
Which of the following options correctly describe the solution process? Select all that apply.
When a solute dissolves in a solvent, solute particles disperse throughout the solvent. When a solute dissolves in a solvent, solute particles react chemically with the solvent molecules.
If a particular solution process is endothermic, then it will be accompanied by ______ in the disorder of the system.
an increase
When solute particles dissolve in a solvent, both solvent-solvent interactions and solute-solute interactions are _____ and solute-solvent interactions are _____.
broken; formed
The solubility of a gas in water usually _____ with increasing temperature.
decreases
Freezing point _____ is observed for solutions containing the appropriate solute. The vapor pressure of a solution is _____ than that of the pure solvent and the solution therefore freezes at a _____ temperature.
depression; lower; lower
The solution process is governed by two factors, _____ and a tendency toward more _____.
enthalpy; disorder
A solution containing 1 mole of a strong electrolyte will have a(n) _____ effect on the colligative properties of the solution than 1 mole 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 mole of a strong electrolyte than for 1 mole 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
An increase in pressure will cause the solubility of a gas to _____, whereas the solubility of a liquid or solid will usually _____.
increase; not change much
The dispersed particles in a colloid are ______ the solute particles in a solution.
larger than
Which of the following expressions correctly represent the percent by mass of a solute in a solution? Select all that apply.
mass of solute / mass of solution x 100 mass of solute / mass of solute + mass of solvent x 100
Percent by mass expresses the concentration of a solution as a ratio of ______.
mass to mass
The ratio mol of solute / L of solution is called the _____ of a solution (symbol M), whereas the _____ (symbol m) of the solution is expressed as mol of solute / kg of solvent. For an aqueous solution, these two quantities will be very similar if the solution concentration is _____.
molarity; molality; low
Which answer choice correctly expresses the van't Hoff factor for a solute?
moles of particles in solution / moles of solute dissolved
Most solids become _____ soluble in a particular solvent at higher temperatures than at lower temperatures, although there are some exceptions.
more
A saturated solution of a gas in a liquid (in a closed system) is at equilibrium with a fixed number of gas molecules leaving and entering the solution every second. If the pressure on the system is increased, _____ molecules of gas strike the surface of the liquid and therefore _____ molecules of gas dissolve in the liquid. A gas is therefore _____ soluble at higher pressures.
more; more; more
Consider the solubility of Na2SO4(s) and O2(g) in water. A large change in atmospheric pressure will have a ______ effect on the solubility of Na2SO4, and a ______ effect on the solubility of O2.
negligible; significant
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 formula mass of solute / mass of solution x 100 expresses the concentration of a solution as _____.
percent by mass
The measure of the amount of a solute that will dissolve in a given solvent at a particular temperature is called its ______.
solubility
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
