Chapter 12: Intermolecular Forces

Question 1

intramolecular forces

Answer 1

forces within a molecule

Question 2

intermolecular forces

Answer 2

forces between molecules (minimum of 2)

Question 3

dipole-dipole interactions

Answer 3

both 1st and 2nd substances are polar (can be the same and different molecules)

Question 4

ion-dipole interactions

Answer 4

results from attraction between an ion and a polar neutral molecule (or dipole)

Question 5

induced-dipole interactions

Answer 5

when an ion or a dipole induces a dipole in an atom or a molecule with no dipole

Question 6

dipole-induced interactions

Answer 6

1st substance is polar, 2nd is not (occurs between a dipole-nonpolar or a dipole-atom)

Question 7

ion-induced dipole

Answer 7

occurs between an ion and a nonpolar molecule, or an ion and an atom

Question 8

dispersion forces

Answer 8

also known as van der Waals or London dispersion forces (induced dipole-dipole interactions) weakest of the IMFs

Question 9

factors that affect dispersion forces

Answer 9

polarizability of the electron clouds and molecular shape

Question 10

hydrogen bond

Answer 10

polar molecules containing H atoms bonded directly to the most electronegative atoms (F, O, or N)

Question 11

why do low molar mass compounds have high boiling points?

Answer 11

because of hydrogen bonding, not molar mass

Question 12

surface tension

Answer 12

increases with the strength of IMF and decreases with rising temperatures, a property related to the tendency of a liquid to seek a shape that yields the minimum surface area

Question 13

cohesive forces

Answer 13

intermolecular forces between like molecules (eg. forces between H2O and H2O)

Question 14

adhesive forces

Answer 14

intermolecular forces between unlike molecules (eg. forces between H2O and glass)

Question 15

concave meniscus

Answer 15

attraction of water to glass is greater than water to water

Question 16

convex shaped

Answer 16

attraction of mercury to mercury is greater than mercury to glass

Question 17

viscosity

Answer 17

measure of a fluid’s resistance to flow, increases with intermolecular forces and decreases with temperature

Question 18

evaporation

Answer 18

surface process (first the molecules on the surface must go to the vapor state and the rest will follow

Question 19

factors that affect evaporation

Answer 19

surface area, temperature, and strength of IMF (high surface area -> high rate of evaporation -> high vapor pressure)

Question 20

which would evaporate quicker? a dish or a flask

Answer 20

the dish due to the larger surface area

Question 21

as temp increases:

Answer 21

more molecules have the minimum KE needed to enter the gas phase (the number of molecules in the gas phase increases, as well as the vapor pressure)

Question 22

vapor pressure

Answer 22

the pressure exerted by a liquids vapor when the liquid and vapor are in equilibrium

Question 23

ethylene glycol with the strongest IMFs will have

Answer 23

high boiling point, low rate of vaporization, and low vapor pressure

Question 24

diethyl ether with the weakest IMFs will have

Answer 24

low boiling point, high rate of vaporization, high vapor pressure

Question 25

what is the boiling point?

Answer 25

temperature at which a liquids vapor pressure equals atmospheric (external) pressure

Question 26

boiling point increases as

Answer 26

IMFs increase