Intermolecular Forces (IMFs) and Solubility

Question 1

Define Ion-Ion interactions

Answer 1

attraction of oppositely charged ions

ex. Na⁺– Cl^-

Question 2

Define Dipole-Dipole interactions

Answer 2

a positive end of of one molecule’s net dipole is attracted to the negative end of another’s

Question 3

Define Hydrogen Bonding

Answer 3

requires an interaction between an H-bond donor and an H-bond acceptor

Question 4

What is a Hydrogen-bond donor

Answer 4

A covalent bond X—-H, where X is a highly electrongative atom, such as N, O, or F

Question 5

What is a Hydrogen-bond acceptor

Answer 5

An acceptor can be any atom with a large concentration of negative charge and a lone pair of electrons.

For the hydrogen-bond to be substantial, un uncharged H-bond acceptor much be F, O, or N

Question 6

Define polar protic solvent

Answer 6

has a net molecular dipole and H-bond donors and acceptors

Question 7

Define polar aprotic solvent

Answer 7

has a net molecular dipole and H-bond acceptors

(lacks H-bond donors)

Question 8

What is the main intermolecular interaction (IMI) between nonpolar molecules?

Answer 8

Induced Dipole Interactions

(London Dispersion Forces)

Question 9

Will more surface area create stronger or weaker induced dipole interactions?

Answer 9

stronger

(more surface area –> stronger induced dipole interactions)

Question 10

Do hydrocarbon fragments increase or decrease solubility?

(is CH₃OH more soluble or less soluble than CH₃(CH₂)₃OH ?)

Answer 10

hydrocarbon fragments decrease solubilty because they are hydrophobic

(CH₃OH is more soluble than CH₃(CH₂)₃OH)

Question 11

Organize from Strongest to Weakest IMF

induced dipole interactions, H-bonding, ion-ion interactions, dipole-dipole interactions, ion-dipole interactions

Answer 11

(Strongest) Ion-ion interactions –>

ion-dipole interactions –>

H-bonding –>

dipole-dipole interactions –>

induced dipole (Weakest)