Chapter 11 key terms

Question 1

As temperature decreases, what happens to particles?

Answer 1

they get closer together

Question 2

What 5 physical properties reflect intermolecular forces?

Answer 2

boiling points, melting points, viscosity, surface tension, capillary action

Question 3

Types of intermolecular bonds from weakest to strongest?

Answer 3

Dispersion forces, dipole-dipole forces, hydrogen bonding, ion dipole

Question 4

How is a dispersion force created?

Answer 4

a nonpolar particle can be temporarily polarized to create a dispersion force

Question 5

What 3 factors determine how strong the dispersion force is?

Answer 5

1. number of electrons(more electrons, more dispersion force)
2. size of atom or molecule/molecular weight(more compact, more dispersion force)
3. shape of molecules with similar masses(more compact, less dispersion force)

Question 6

Do molecules with lower boiling points have weaker or stronger intermolecular forces?

Answer 6

weaker

Question 7

When do dipole-dipole interactions occur?

Answer 7

in polar molecules

Question 8

For molecules of approximately equal mass and size, the more polar the molecule, the higher or lower its boiling point?

Answer 8

higher

Question 9

Which has a greater effect: Dipole-dipole interactions or dispersion forces?

Answer 9

-if two molecules are of similar size and shape, dipole-dipole will most likely be the dominating force
-if one molecule is significantly larger than another, dispersion forces will likely determine its physical properties

Question 10

What are ion-dipole forces?

Answer 10

found in solutions of ions
-strength of these forces is what makes it possible for ionic substances to dissolve in polar solvents, like water

Question 11

What is viscosity?

Answer 11

resistance of a liquid to flow

Question 12

What 8 liquid properties are affected by intermolecular forces?

Answer 12

boiling point, melting point, viscosity, surface tension, capillary action, heats of vaporization, heats of fusion

Question 13

When does viscosity increase?

Answer 13

with stronger intermolecular forces

Question 14

When does viscosity decrease?

Answer 14

with higher temperature

Question 15

What is a phase change?

Answer 15

conversion from one state of matter to another

Question 16

What happens to energy in a phase change?

Answer 16

Its either added(endothermic) or released(exothermic)

Question 17

What are the 3 pairs of phase changes?

Answer 17

melting/freezing, vaporizing/condensing, subliming/depositing

Question 18

What phase changes are endothermic?

Answer 18

melting/fusion, vaporization, sublimation

Question 19

What phase changes are exothermic?

Answer 19

condensation, freezing, deposition

Question 20

What is the heat of fusion?

Answer 20

energy required to change a solid at its melting point to a liquid

Question 21

What is the heat of vaporization?

Answer 21

the energy required to change a liquid at its boiling point to a gas

Question 22

What is the heat of sublimation?

Answer 22

the energy required to change a solid directly to a gas

Question 23

During a phase change does temperature of the substance change?

Answer 23

NO, which means melting point and boiling point also don’t change

Question 24

In a heating curve, what is the enthalpy change (heat, q) the product of?

Answer 24

its the product of the mass or moles and the heat of fusion or vapoization

Question 25

What is a heating curve?

Answer 25

a graph of temperature versus heat

Question 26

What do the horizontal lines of a heating curve represent?

Answer 26

one for melting and one for vaporization -horizontal because temp doesn't change

Question 27

What is a supercritical fluid?

Answer 27

the state of a gas beyond the critical temperature

Question 28

What is critical temperature?

Answer 28

the temperature beyond which a gas cannot be compressed

Question 29

What happens to most gases when pressure is applied?

Answer 29

they liquify

Question 30

What is critical pressure?

Answer 30

the pressure needed to compress the liquid at a critical temperature

Question 31

What is vapor pressure?

Answer 31

the state of dynamic equilibrium between liquid molecules evaporating and vapor molecules condensing

Question 32

When does the boiling point of a liquid occur?

Answer 32

its the temperature at which the vapor pressure equals the atmospheric pressure

Question 33

What is the relationship between pressure and temperature?

Answer 33

inverse

Question 34

What is a phase diagram?

Answer 34

graph showing states of matter under conditions of temperature and pressure

Question 35

What happens at the triple point?

Answer 35

all phases are present

Question 36

What happens at the critical point?

Answer 36

supercritical fluid