Chapter 13 Chem 2

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

Which of the following statements correctly describe different types of mixtures? Select all that apply.

The composition of any mixture is variable. A heterogeneous mixture contains two or more different phases. Differences in particle size account for the main differences between solutions and colloids.

A solution usually has a _____ entropy than either the pure solvent or pure solute because in the solution there are a _____ number of interactions between particles and therefore _____ ways to distribute the energy of the system.

higher, greater, more

The charge density of an ion has a significant effect on its heat of hydration. The _____ the charge on an ion and the _____ its size, the greater its attraction to the H2O molecules surrounding it and the more _____ the value of ΔHhydr of the ion.

higher, smaller, negative

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 the heat of solvation, ΔHsolvation, and heat of hydration, ΔHhydr, for a solution process? Select all that apply

ΔHsolvation = ΔHsolvent + ΔHmix ΔHsoln = ΔHsolute + ΔHsolvation (when water is a solvent it becomes this)

Which of the following statements correctly describe the components of the aqueous heats of solution, ΔHsoln? Select all that apply.

-ΔHsoln = ΔHlattice + ΔHhydr of the ions -ΔHlattice is always a positive value.

Which of the following statements correctly relate the charge density of an ion to heat of hydration? Select all that apply.

An ion with a higher charge density has a more negative heat of hydration than an ion of similar size but lower charge. As the charge on an ion increases and its radius decreases, its charge density will increase and so will the magnitude of the heat of hydration. (Notes: As an ion becomes smaller and more highly charged its charge density will increase.As the charge density of an ion increases the heat of hydration becomes more negative, i.e., its magnitude increases.)

Match the periodic trends in the heat of hydration based on charge density.

Down a group: ΔHhydr decreases as charge densities decrease. From left to right across a period: ΔHhydr increases as charge densities increase.

Which of the following statements correctly describe the enthalpy changes associated with the formation of a solution? Select all that apply.

Energy is released when the solvent and solute particles attract each other and mix to form a solution. The overall enthalpy change for the solution process depends on the balance of energy absorbed vs. energy released. Energy is absorbed to separate the solvent particles from each other.

Which of the following statements correctly describe the change in entropy when a solution is formed? Select all that apply.

Entropy usually increases when a solution forms because there are more interactions between particles in a solution. The particles in a solution generally have a greater freedom of movement than the particles in a pure solute.

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

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

Match each type of intermolecular force correctly to the type of solution in which each is exhibited.

Ion-dipole forces - An ionic solute in a polar solvent Ion-induced dipole forces: A nonpolar solute in a polar solvent that also contains dissolved ions Dipole-induced dipole forces: A nonpolar solute in a polar solvent Dispersion forces :Present in all solutions; principal intermolecular force when both solvent and solute are nonpolar

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

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

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 number of moles present

Match each term with the correct definition, with reference to the composition of a solution.

Solute- The component present in the smallest amount Solvent - The component present in the largest amount. Solubility-The maximum amount of a solute that can dissolve in a fixed quantity of a particular solvent at a given temperature correct. Miscible-The substances are soluble in each other at any quantity correct.

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 step(s), involved in the formation of a solution, is/are associated with a positive sign for ΔH? Select all that apply.

Solvent particles separate from each other. Solute particles separate from each other. (Energy is released when come together which results in a neg sign)

What does the term "like dissolves like" mean?

Substances that have similar types of intermolecular forces dissolve in each other.

Which of the following statements correctly describe entropy? Select all that apply.

The entropy of a gas is higher than the entropy of a liquid. Entropy is related to the freedom of motion of the particles in a system. Entropy is related to the number of ways a system can disperse its energy.

Which of the following statements correctly describe solubility? Select all that apply.

The solubility of a given substance in a particular solvent varies with temperature. A concentrated solution contains a relatively large amount of solute in a given amount of solvent.

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

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

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

True

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

Match each term describing solutions with the correct definition.

Unsaturated: a solution that contains less than the equilibrium concentration of dissolved solute; more solute added will dissolve Saturated: a solution containing the maximum amount of dissolved solute; more solute added will not dissolve SuperSaturated: a solution containing more than the equilibrium concentration of solute; the solution is unstable and solute will separate from it readily

The magnitude of the heat of hydration of an ion _____ down a group on the periodic table and _____ from left to right across a period. (The term magnitude indicates the value of the heat of hydration, not its sign.)

decreases, increases

The terms "concentrated" and "dilute" describe the relative amounts of dissolved solute in a given solvent. A(n) _____ solution has a smaller amount of solute in the same amount of solvent than a(n) _____ solution.

dilute; concentrated

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

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

Entropy (S) is related to the ___________ of movement of the particles in a system. The particles of a solid are highly ordered and therefore have __________ freedom of movement than the particles of a liquid. A liquid has __________ entropy than a solid.

freedom, less , more

A solution is a _____ mixture, meaning it exists in one phase, whereas a colloid is a _____ mixture with two or more phases in its composition.

homogeneous; heterogeneous

Solvent water molecules will cluster around dissolved ions to form ______, which stabilize the solute in the aqueous solution.

hydration shells

Substances that have similar __________ forces are able to dissolve in each other, giving rise to the phrase "like __________ like."

intermolecular; dissolves

When an ionic compound is dissolved in water, the overall enthalpy change ΔHsoln is the combination of the _____ energy, which is the energy required to separate the ions, and the heat of _____ of the ions.

lattice; hydration

For very dilute solutions, two terms are often used to express concentration (type the abbreviation):

mass of solute/mass of solution x 10^9 = ppb mass of solute/mass of solution x 10^6 = ppm

Solubility is defined as the __________ amount of solute that is able to dissolve in a fixed amount of a particular solvent at a particular _________ and pressure.

maximum; temperature

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

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

Which of the following options give the correct formula to calculate the concentration of a solution in ppm and ppb by mass? Select all that apply.

ppb = mass of solutemass of solutionmass of solutemass of solution x 109 ppm = mass of solutemass of solutionmass of solutemass of solution x 106

A solution that contains the maximum amount of dissolved solute in a fixed quantity of solvent at a particular temperature is called a(n) _________ solution. This type of solution will have some _________ solute present, which will be in equilibrium with the dissolved solute.

saturated, undissolved

When an ionic solute dissolves in water, the ions ________ and each ion becomes surrounded by a cluster of H2O molecules called a(n) __________ shell.

separate; hydrogen

Match the solution term with its correct description: concentrated, dilute

Concentrated: A relatively large amount of solute dissolved in a given quantity of solvent Dilute: A relatively small amount of solute dissolved in a given quantity of solvent

Which of the following statements correctly describe the heat of solvation for a solution process? Select all that apply.

If ΔHhydr < 0, then more energy is released due to solvent-solute attraction than the energy absorbed in separating solvent particles. The heat of solvation is called the heat of hydration if H2O is the solvent. The heat of solvation is the enthalpy change that occurs when a solute particle is surrounded by solvent particles. (Notes: Heat of solvation refers only to the separation of solvent particles and the process of surrounding a solute particle with solvent particles. It does not include the energy required to separate the solute particles from each other.)