Chp. 13.1 - Types of Solutions: Intermolecular Forces and Solubility

Question 1

It dissolves in a solvent to form a solution.

Answer 1

Solute

Question 2

Solvent

Answer 2

In general, the most abundant component

Question 3

Soluble in each other in any proportion

Answer 3

Miscible

Question 4

The maximum amount that dissolves in a fixed quantity of a given solvent @ a given temperature, where an excess of the solute is present.

Answer 4

Solubility

Question 5

The rule-of-thumb “like dissolves like”.

Answer 5

Substances with similar types of intermolecular forces dissolve in each other.

Question 6

_______ forces are the principal force involved when an ionic compound dissolves in water.

Answer 6

Ion-dipole

Question 7

As an ion separates, water molecules cluster around it in ________________.

Answer 7

hydration shells

Question 8

In the innermost hydration shell, normal _____ bonding is disrupted to form the ___________ forces.

Answer 8

H, ion-dipole

Question 9

______ bonding if the principal force in solutions of polar, O- and N-containing organic and biological compounds.

Answer 9

H

Question 10

In the absence of H-bonding, ____________ allow polar molecules like propanal (CH3CH2CHO) to dissolve in polar solvents like dichloromethane (CH2Cl2).

Answer 10

dipole-dipole forces

Question 11

A type of charge-induced dipole force that relies on polarizability. It arises when an ion’s charge distorts the electron cloud of a nonpolar molecule.

Answer 11

Ion-induced dipole forces

Question 12

__________ forces are based on polarizability and arise when a polar molecule distorts the electron cloud of a nonpolar molecule. They are _________ than ion-induced dipole forces because the charge of each pole is less than an ion’s (Coulomb’s law).

Answer 12

Dipole-induced dipole; weakerRank

Question 13

__________ forces contribute to the solubility of ___ solutes and ____ solvents, but they are the ______ intermolecular force in solutions of _______ substances.

Answer 13

Dispersion; all; all; principal; nonpolar

Question 14

Rank the following forces in order of decreasing strength (kJ/mol):

Dipole-dipole
H-bond
Dispersion
ion-dipole
dipole-induced dipole
ion-induced dipole

Answer 14

Ion-dipole (40-600)
H bond (10-40)
Dipole-dipole (5-25)
Ion-induced dipole (3-15)
Dipole-induced dipole (2-10)
Dispersion (0.05-40)

Question 15

Salts are ______ in water. Why?

Answer 15

soluble; Like-Dissolves-Like Rule. The strong ion-dipole attractions between ion and water are similar to the strong attractions between ions and the strong H bonds between water molecules, so they CAN replace each other.

Question 16

Salts are __________ in hexane (C6H14). Why?

Answer 16

insoluble; The weak ion-induced dipole forces between ion and nonpolar hexane CANNOT replace attractions between the ions.

Question 17

Oil is _______ in water. Why?

Answer 17

insolube; The weak dipole-induced dipole forces between oil and water molecules CANNOT replace the strong H bonds within water molecules and the extensive dispersion forces within the oil.

Question 18

Oil is __________ in hexane. Why?

Answer 18

soluble; The dispersion forces in one readily replace dispersion forces in the other.

Question 19

The general formula for an alcohol

Answer 19

CH3(CH2)_nOH

Question 20

Solubility in water is high for smaller alcohols. True or False?

Answer 20

True.

Question 21

Table 13.2: Solubility of a Series of Alcohols in Water and in Hexane. Complete the chart.

Alcohol Sol. in H20 Sol. in Hexane

CH3OH
(methanol)

CH3CH2OH
(ethanol)

CH3(CH2)2OH
(1-propanol)

CH3(CH2)3OH
(1-butanol)

CH3(CH2)4OH
(1-pentanol)

CH3(CH2)5OH
(1-hexanol)

Answer 21

Table 13.2: Solubility of a Series of Alcohols in Water and in Hexane. Complete the chart.

Alcohol Sol. in H20 Sol. in Hexane

CH3OH <><> 1.2
(methanol)

CH3CH2OH <><> <><>
(ethanol)

CH3(CH2)2OH <><> <><>
(1-propanol)

CH3(CH2)3OH 1.1 <><>
(1-butanol)

CH3(CH2)4OH 0.30 <><>
(1-pentanol)

CH3(CH2)5OH 0.058 <><>
(1-hexanol)

Question 22

Solubility in water is low for larger alcohols. Why?

Answer 22

While the -OH portionof such an alcohol forms H bonds to water, these cannot make up for all the other H bonds between water molecules that have to break to make room for the hydrcarbon portion.

Question 23

Why is the solubility high for smaller alcohols?

Answer 23

When they mix with water, H bonding in solute and solven is replaced by H bonding between solute and solvent.

Question 24

Solubility in hexane is _______ for the smallest alcohol. Why?

Answer 24

low; In addition to dispersion forces, weak dipole-induced dipole forces exist between the -OH of methanol (CH3OH) and hexane. These cannot replace the strong H bonding between CH3OH molecules, so its solubility is low.

Question 25

Solubility in hexane is ______ for larger alcohols.

Answer 25

high

Question 26

Which solvent will dissolve more:

Sodium chloride in methanol (CH3OH) or in 1-propanol (CH3CH2CH2OH)?

Answer 26

Methanol. NaCl is ionic, so it dissolves through ion-dipole forces. Both methanol and 1-propanol have a polar -OH group, but the hydrocarbon portion of each alcohol interacts only weakly with the ions and 1-propanol has a larger hydrocarbon than methanol.

Question 27

Which solvent will dissolve more:
Ethylene glycol (HOCH2CH2OH) in hexane (CH3CH2CH2CH2CH2CH3) or in water?

Answer 27

Water.

Question 28

Which solvent will dissolve more:
Diethyl ether (CH3CH2OCH2CH3) in water or in ethanol (CH3CH2OH)?

Answer 28

Ethanol

Question 29

If similar intermolecular forces occur in solute and solvent, they replace each other when the substances mix and a ____ is likely to form. (“like dissolves like”)

Answer 29

Solution

Question 30

When _____ compounds dissolve in water, the ____ become surrounded by hydration shells of H-bonded water molecules.

Answer 30

ionic; ions

Question 31

Solubility of organic molecules in various solvents depends on the relative sizes of their _____ and ______ portions.

Answer 31

polar; nonpolar

Question 32

The solubility of nonpolar gases in water is low because of ____ intermolecular forces. Gases are _____ with one another, and they ______ in solids by fitting into spaces between the closely packed particles.

Answer 32

weak; miscible; dissolve

Question 33

Solid-solid solutions include ______ and ______.

Answer 33

alloys; waxes