Chp. 13.1 - Types of Solutions: Intermolecular Forces and Solubility Flashcards
It dissolves in a solvent to form a solution.
Solute
Solvent
In general, the most abundant component
Soluble in each other in any proportion
Miscible
The maximum amount that dissolves in a fixed quantity of a given solvent @ a given temperature, where an excess of the solute is present.
Solubility
The rule-of-thumb “like dissolves like”.
Substances with similar types of intermolecular forces dissolve in each other.
_______ forces are the principal force involved when an ionic compound dissolves in water.
Ion-dipole
As an ion separates, water molecules cluster around it in ________________.
hydration shells
In the innermost hydration shell, normal _____ bonding is disrupted to form the ___________ forces.
H, ion-dipole
______ bonding if the principal force in solutions of polar, O- and N-containing organic and biological compounds.
H
In the absence of H-bonding, ____________ allow polar molecules like propanal (CH3CH2CHO) to dissolve in polar solvents like dichloromethane (CH2Cl2).
dipole-dipole forces
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.
Ion-induced dipole forces
__________ 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).
Dipole-induced dipole; weakerRank
__________ forces contribute to the solubility of ___ solutes and ____ solvents, but they are the ______ intermolecular force in solutions of _______ substances.
Dispersion; all; all; principal; nonpolar
Rank the following forces in order of decreasing strength (kJ/mol):
Dipole-dipole H-bond Dispersion ion-dipole dipole-induced dipole ion-induced dipole
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)
Salts are ______ in water. Why?
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.
Salts are __________ in hexane (C6H14). Why?
insoluble; The weak ion-induced dipole forces between ion and nonpolar hexane CANNOT replace attractions between the ions.
Oil is _______ in water. Why?
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.
Oil is __________ in hexane. Why?
soluble; The dispersion forces in one readily replace dispersion forces in the other.
The general formula for an alcohol
CH3(CH2)_nOH
Solubility in water is high for smaller alcohols. True or False?
True.
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)
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)
Solubility in water is low for larger alcohols. Why?
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.
Why is the solubility high for smaller alcohols?
When they mix with water, H bonding in solute and solven is replaced by H bonding between solute and solvent.
Solubility in hexane is _______ for the smallest alcohol. Why?
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.
